Douglas Richardson, Royal Ancestry: A Study in Colonial and Medieval Families, 2nd edition (Salt Lake City, Utah, 2013), volume IV, pages 562-564.

6. GEOFFREY DE SAY, Knt. of Edmonton, Middlesex, West Greenwich, Birling, Cudham, and Keston, Kent, Leckhampstead, Buckinghamshire, Kimpton and Sawbridgeworth, Hertfordshire, Hartwell, Northamptonshire, Allington and Hamsey, Streat, etc., Sussex, etc., 2nd but eldest surviving son, probably born about 1180. In the period, 1197-8, he confirmed his father's grant of the manor of Rickling, Essex, to his half-brother, Geoffrey de Say. In 1198 he and his father, Geoffrey de Say the elder, granted the woods of Periers and the church of St. Nicholas of Monnouval to the hospital of Drincourt, providing for prayers for the soul of Alice de Cheyne, mother of the younger Geoffrey, and for William her other son. He married before 1215 HAWISE DE CLARE, daughter of Richard de Clare, Knt., 3rd Earl of Hertford (but generally styled Earl of Gloucester [...]. They had three sons, William, Knt., Geoffrey, and John, Knt. In 1202 Ralph Tesson, Seneschal of Normandy, was ordered to see that Geoffrey de Say the younger had a hundred liberates of the land of Juhel de Mayenne to replace the land which he had lost through the war. In 1208 the Sheriff of Kent was directed to put Geoffrey de Say the younger into possession of the moiety of the manor of Bourne (in Bishopsbourne), Kent which Ralph Tesson formerly held. In 1214 he made fine in 400 marks to have his father's lands, and in the same year the sheriffs of Kent, Herts, Bucks, Sussex, Middlesex, and Northampton had orders to give him seisin of the lands which had been his father's. In 1214 he confirmed the gift made by his parents, Geoffrey and Alice, to the canons of St. Mary's, Bayham of the advowson of the church of St. Nicholas, Greenwich, Kent. He joined the confederacy of the barons against King John. He was one of the twenty-five barons elected to guarantee the observance of Magna Carta, signed by King John 15 June 1215. In October 1215 the king gave all of Geoffrey's lands except the manor of West Greenwich, Kent to Peter de Craon. In Nov. 1215 Geoffrey de Say, Richard, Earl of Clare, Robert Fitz Walter, and the mayor and two or three or four citizens of London had letters of safe-conduct to speak with the Bishop of Winchester and others to treat of peace between the king and the barons. He was taken prisoner at the Battle of Lincoln 20 May 1217. In July 1217 two of his knights had safe-conduct to go to London as hostages. Having returned to fealty, he had restoration of his lands 14 Sept. 1217. He and Pernel Pirot renounced any claim in the advowson of Leckhampstead, Buckinghamshire before 1219. He went on pilgrimage to the Holy Land in 1219, and to Santiago de Compostella in Spain in 1223, He witnessed a charter of William de Warenne, Earl of Surrey c. 1220. He was present at the Siege of Bytham Castle in 1221. In 1222 he was granted a weekly fair at Sawbridgeworth, Hertfordshire. In 1224 he answered for 42 knights’ fees in the scutage of Montgomery. In the period, 1226-30, he founded a Preceptory of the Knights Templar at Saddlescombe, Sussex, in exchange the manor of West Greenwhich, Kent which had been granted to them by his father. At an unknown date, he granted land in Edmonton, Middlesex to Ralph Silvan, together with a covenant not to alienate the property to religious persons or Jews. By an undated charter, he granted five acres of land in West Greenwich, Kent to Symon de Thycheseia. At an unknown date, he confirmed the gift of his cousin, Walkelin Mamimot, to Bermondsey Abbey of a rent-charge of 60 shillings per annum out of the lordship of Chippenham in Dillehurst. At an unknown date, he gave Alice Blund of Edmonton, Middlesex ½ virgate of land which Reginald Fitz Ralph formerly held in the manor of Edmonton of him, to be held by service of 5s. per annum. SIR GEOFFREY DE SAY died while in service in Poitou 19 August 1230. He was buried at the Hospital of St. Mary, Dover, Kent, to which he had given the manor of Coldred with his body. His widow, Hawise, joined their son, William de Clare, in a charter dated c.1235 regarding property in Edmonton, Middlesex.
[Note: The marital history of Geoffrey de Say is quite muddled in secondary sources. C.P. 11 (1949): 470 (sub Say) states that Geoffrey de Say, the Magna Carta baron, married (1st) Alice, widow of Hugh de Periers, and heiress and possibly daughter of John de Cheyney, yet contemporary records clearly show that Alice de Cheyney was actually this Geoffrey's mother. C.P. further states that Geoffrey married (2nd) Margery Briwerre (or Brewer), widow of [William] de la Ferté and Eudes de Dammartin, yet this woman was actually the 2nd wife of his half-brother, Geoffrey de Say (died 1265/71), of Rickling, Essex, Denham, Suffolk, etc.25 New research indicates that Geoffrey de Say, the Magna Carta baron, actually married Hawise de Clare, daughter of Richard de Clare, Earl of Hertford. Gerald Paget notes that Geoffrey de Say had scutage of the knights fees 7 March 1215, which he held of the Earl of Clare in free-marriage (see Paget Baronage of England (1957) 485: 3-4 (sub Say), cites Cl. 16 John m. 7). About 1235 Geoffrey's widow, Hawise, and their son, William de Say, jointly issued a charter regarding property in Edmonton, Middlesex, (see O'Connor Cal. Cartularies of John Pyel & Adam Fraunceys (Camden Soc. 5th Ser. 2) (1993): 240).]

Brydges Collins' Peerage of England 7 (1812): 16-39 (sub Twisleton, Lord Say and Sele) (identifies wife of Geoffrey de Say died 1230 as Alice, "daughter and co-heir of John de Caisneto, or Cheney," which Alice was actually his mother; an earlier Geoffrey de Say is assigned a wife "Hawise, daughter of ___ de Clare.") Dugdale Monasticon Anglicanum 5 (1825): 87; 6(2) (1830): 657, 913 (confirmation charter of Geoffrey de Say; charter names his parents, Geoffrey and Aliz). Clutterbuck Hist. & Antiqs. of Hertford 3 (1827): 190-194 (Mandeville-Say ped.). Thomson Hist. Essay on the Magna Charta of King John (1829): 295 (biog. of Geoffrey de Say). Roberts Excerpta è rotulis finium in Turri Londinensi 1 (1835): 202. Hardy Rotuli de Liberate ac de Misis et Præstitis, Regnante Johanne (1844): 191, 207, 216, 228, 229. Eyton Antiqs. of Shropshire 3 (1856): 331-333. Sussex Arch. Colls. 9 (1857): 149-150; 65 (1924): 20-53 (re. Cheyne fam.); 66 (1925): 181-182. Top & Gen. 3 (1858): 1-4 (erroneously identifies wife as "Alice, daughter of John de Cheney"). Paris Chronica Majora 2 (Rolls Ser. 57) (1874): 604-605. Stubbs Historical Works of Gervase of Canterbury 2 (Rolls Ser. 73) (1880): 110-111. Desc. Cat. Ancient Deeds 2 (1894): 30 (A. 2035), 492-504. Round Cal. Docs. Preserved in France 1 (1899): 95 (charter of Geoffrey de Sai and of Geoffrey, son of the said Geoffrey and Aeliza de Kaisneio, dated 1198). C.P.R. 1216-1225 (1901): 369. Misc. Gen. et Heraldica 4th Ser. 3 (1910): 313-317. Phillimore Rotuli Hugonis de Welles Episcopi Lincolniensis 1209-1235 1 (Lincoln Rec. Soc. 3) (1912): 109-110. VCH Hertford 3 (1912): 29-33, 332-347. Genealogist n.s. 34 (1918): 181-189 (two charters of Geoffrey de Say [died 1230], one dated c. 1198 naming his father was "William son of Geoffrey de Say;" the other charter undated naming his mother as "Alicie de Chetnay."). Farrer Honors & Knights' Fees 3 (1925): 226, 313-322. VCH Buckingham 4 (1927): 181 (Say arms: Quarterly or and sable). Salzman Chartulary of the Priory of St. Pancras of Lewes 1 (Sussex Rec. Soc. 38) (1932): 49-50 (charter of William de Warenne, Earl of Surrey). Siedschlag English Participation in the Crusades 1150-1220 (1939): 138. VCH Sussex 7 (1940): 114. Hethe Reg. Hamonis Hethe Diocesis Roffensis 1 (Canterbury & York Soc. 48) (1948): 24. C.P. 11 (1949): 468-470 (sub Say). Hatton Book of Seals (1950); 325-326. Paget Baronage of England (1957) 485: 1-10 (sub Say). Sanders English Baronies (1960): 98, 135. Curia Regis Rolls 14 (1961): 327, 332-333; 15 (1972): 110, 366, 384. Powicke Loss of Normandy (1961): 351. Loyd Origins of Some Anglo-Norman Fams. (1975): 27-28 (sub Chesney, de Caisneto, etc.), 76. Harper-Bill Stoke by Clare Cartulary 1 (Suffolk Charters 4) (1982): 31. Burman Templars: Knights of God (1990): 96. O'Connor Cal. Cartularies of John Pyel & Adam Fraunceys (Camden Soc. 5th Ser. 2) (1993): 221 (charter of Geoffrey de Say), 240 (charter of William son of Geoffrey de Say and Hawise de Clare). VCH Northampton 5 (2002): 176-197. Corporation of London Recs. Office: Bridge House Estates, CLA/007/EM/02/F/014 (undated charter of Geoffrey de Say to Symon de Thycheseia) (available at www.a2a.org.uk/search/index.asp). 25 Care should be taken to distinguish Sir Geoffrey de Say, the Magna Carta baron, from his younger half-brother, Sir Geoffrey de Say (1265/71), of Rickling, Essex, and Denham, Suffolk, which half-brother was the son of Geoffrey de Say the elder, died 1214, by his 2nd wife, Alice, daughter of Aubrey de Vere, Earl of Essex. The younger Sir Geoffrey appears to have married three times: (1st) to an unknown wife; (2nd) before Michaelmas 1225 (date of lawsuit) Margery Briwerre, widow of William de la Ferté (died 1216) and Eudes de Dammartin (died shortly before 8 April 1225), which Geoffrey and Margery were divorced without issue probably by Hilary term 1230 (when Margery occurs alone in a lawsuit as Margery de la Ferté) and definitely by Trinity term, 1231 (Margery died in or before 1237); and (3rd) before 1239-40 (date of fine) Aline ___, widow of Hubert de Vaux (living 1235/6), of Surlingham, Suffolk. By these various marriages, he had at least two sons, Geoffrey and Robert (clerk), and one daughter, Maud (wife of Geoffrey Crek). His third wife, Aline, was living in Hilary Term, 1244. In 1265 Sir Geoffrey was granted free warren in his demesne lands at Rickling, Essex and Denham, Suffolk. He died before 1271. His heir in 1273 was John de Say, Knt., of Denham, Suffolk and Rickling, Essex, who in that year with his brother, Nicholas de Say, beat wounded, and ill treated John Mauveisin, bailiff of the hundred of Risbridge, who came to levy the king's due from the said John in the vill of Denham. In 1292 Sir John de Say confirmed a grant of Robert de Say, clerk, son of Sir Geoffrey de Say, in Rickling, Essex. Sir John de Say was living in 1294. Rye Short Cal. of Feet of Fines for Norfolk 1 (1885): 63; Maitland Bracton's Note Book 2 (1887): 445-446; Dallas & Porter Note-book of Tristra Risdon (1897): 74-75; Desc. Cat. Ancient Deeds 2 (1894): 521; Denham Parish Regs., 1539-1850, with Hist. Notes & Notices (1904): 180-181; VCH Surrey 3 (1911); 321-326; Clay Early Yorkshire Charters 6 (1939): 53-54; C.P. 11 (1949): 467, footnote o (sub Say); Curia Regis Rolls 12 (1957): 295, 302-303, 322; Paget Baronage of England (1957) (citing Cl. 16 John. m.7); Curia Regis Rolls 15 (1972): 110; VCH Cambridge 6 (1978): 52-53; Curia Regis Rolls. 16 (1979): 388, 389, 392, 398; Aston Lollards & Reformers (1984): 181-182 (which erroneously assigns Margery Briwerre as the wife of Geoffrey de Say (died 1230), the Magna Carta baron); Dodwell Charters of Norwich Cathedral Priory 2 (Pubs. Pipe Roll Soc. n.s. 46) (1985): 247-248; Curia Regis Rolls 17 (1991): 131, 133, 287, 426, 479-480; Curia Regis Rolls 18 (1999): 212; VCH Northampton 5 (2002): 374-413; National Archives, C 241/18/95, C 241/25/121, C 241/25/247 (available at www.catalogue.nationalarchives.gov.uk/searsh.asp).