The Gatehouse website record of a licence to crenellate for Thonock Castle Hills granted on 1142 (1146)

libere et quiete tenendum omnibus liberis consuetudinibus cum quibus aliquis comes Anglie tenet castella sua, (Round)

494. Lincoln, William Earl of (probably 1146, at Stamford)
Grant of the manor of Kirton in Lindsey, the castle of Gainsborough (Lincs.), and the bridge over the Trent to William (de Roumare) Earl of Lincoln
Stephanus rex Angl(orum) archiepiscopis episcopis abbatibus comitibus justiciariis vicecomitibus baronibus ministris et omnibus fidelibus suis Francis et Anglis totius Anglie salutem. Sciatis quia dedi et concessi comiti Lincoln(ie) Willelmo hereditarie sibi et heredibus suis manerium meum de Chirchetona cum omnibus ei pertinentibus sicut illud melius tenui dum in mea manu fuit, excepta terra canonicorum Lincoln(iensium) et exceptis centum solidatis terre in Graingeham quas comes Rann(ulphus) tenet de me et heredibus meis, ad tenend(um) cum omnibus liberis consuetudinibus eidem manerio pertinentibus. Et preter hoc concedo ei castrum suum de Geinesburg(o) et pontem suum ultra Trentam libere et quiete tenend(a) cum omnibus liberis consuetudinibus cum quibus aliquis comes Anglie melius et liberius tenet castella sua. Quare volo et firmiter precipio quod comes Willelmus Lincoln(ie) hec omnia predicta bene et in pace et libere et quiete et honorifice teneat. T(estibus) comite Rann(ulpho), et comite Gis(leber)t(o) de Penbroc, et comite Gis(leber)t(o) de Hertf(ord), et comite Sim(one), et comite R(ogero) de Warwic, et comite R(oberto) de Ferr(ariis), et W(illelmo) Mart(el),i et Bald(ewino) filio Gis(leber)t(i), et W. filio Gis- (leber)t(i),- et Ric(ardo) de Canvill(a), et Ric(ardo) lilio Ursi, et E(ustachio) filio Joh(annis), et Rad(ulpho) de Haia, et Hug(one) Wac(a), et W(illelmo) de Colevill(a). Apud Stanf(ordam).
(Gt. Coucher of Duchy of Lancaster), f. 445; B.M. Harley MS. 5019, f. 202" (copied from the original by Richard St. George, c. 1604 with drawing showing Stephen's second seal on a tag); also Add. MS. 5485, f. 86; Bodl. Lib., Rawlinson MS. B. 102, f. 98 (transcript by John Guillin (c. 1605-14) also with drawing of Stephen's second seal).
Date: Round's suggestion of 1142 (G. de M. 159) is almost certainly wrong. See E.H.R. Ixxv (1960), 656-7. Stephen's second seal gives a date after June 1139, and Gilbert E. Pembroke d. 1148. Within these limits. Earl Ranulf was supporting Stephen only in 1139-40 and 1146. The presence of Eustace fitz John who was with the Scots at the battle of the Standard (1138) but later became constable of Chester suggests 1146 as the more likely alternative. The land of the canons of Lincoln in Kirton is puzzling; cf. 473. By 1155 it had reverted to the crown (Pipe Roll 2 Hen. II, p. 24). (Cronne and Davis)

Comments

Round writes this a royal confirmation of William's possession of the castle. For some historians who believed that castles were built "legally" only by permission of the King this treaty is sometimes used as proof for that theory and part of that theory is that licences to crenellate are the usual form of that royal permission. The latin term licentia had, in practice, many meanings but is best translated as "freedom to". This treaty contains neither the term licentia nor crenellate. This is evidence that, even in the Anarchy, some legal forms were in operation and a transfer of holdings were recorded but it is not, in any meaningful sense, a licence to crenellate.

Original source is;

Great Coucher, Vol. 2 fol. 445
Cronne, H.A. and Davis R.H.C. (eds), 1968, Regesta Regum Anglo-Normannorum, 1066–1154 Vol. 3 Regesta regis Stephani ac Mathildis imperatricis ac Gaufridi et Henrici ducum Normannorum, 1135-54 p. 184-5 No. 494 online copy

(In fact, the original source given is usually a transcription/translation of what are precious medieval documents not readily availably. It should be noted that these transcription/translations often date to the nineteenth or early twentieth centuries and that unwitting bias of transcribers may affect the translation. Care should also be taken to avoid giving modern meaning to the medieval use of certain stock words and terms. Licentia is best translated as 'freedom to' not 'permission'.)

Roumare, William de, first earl of Lincoln (c.1096–1155x61)

Roumare, William de, first earl of Lincoln (c.1096–1155x61), justice...During 1137 he attested for King Stephen in Normandy, and was among those appointed as justiciars there. Probably in 1139 Stephen appears to have made him earl of Cambridge, a title he had relinquished by 1142 when he was earl of Lincoln. The most plausible date for his creation as earl of Lincoln is shortly before Christmas 1140, when Stephen visited Lincoln and increased his honours and those of Ranulf, earl of Chester. Stephen's visit may have been intended to deal with Ranulf, who is said to have seized Lincoln Castle in 1140 after the king had helped Henry, the son of King David of Scotland, Ranulf's rival for Carlisle, to avoid a trap which Ranulf had set for him. It is possible that Stephen's grant of increased honours was part of a peace agreement, and included some form of rights in Lincoln Castle. Alternatively, it is possible that Stephen had come in peace to Lincoln and bestowed the comital title, but no rights in the castle, on Roumare, and that Ranulf's seizure of the fortress followed the king's departure. Whatever the case, the half-brothers were besieged by the king when he returned to Lincoln during the Christmas festival of 1140. With the help of Ranulf's father-in-law, Robert, earl of Gloucester, they defeated and captured Stephen at the battle of Lincoln on 2 February 1141. (Dalton)

Biographical source include;

Paul Dalton, Sept 2004, ‘Roumare, William de, first earl of Lincoln (c.1096–1155x61)’ Oxford Dictionary of National Biography (Oxford University Press) online edn, Jan 2008 online copy (subscription may be needed)