The Gatehouse website record of a licence to crenellate for Greenwich granted on 1437 March 6

Licence, with the assent of the lords spiritual and temporal and of the commonalty of the realm of England in the present Parliament, for Humphrey, duke of Gloucester, and Eleanor, his wife, to impark 200 acres of land, pasture, wood, heath and furze at Grenewyche, outside the metes of the forest ; notwithstanding that 40 acres of pasture, heath and furze out of the said 200 acres are parcel of the manor of Grenewych granted to the prior and convent of the house of Jesus of Bethlehem of Shene by its founder, Henry V, and now granted by the said prior and convent to the said duke and duchess in exchange for other lands. Licence also for the said duke and duchess to crenellate their manor- house or mansion of Grenewych, and to build and crenellate a tower within the said park. By pet. in Parl. (CPR)

Pro Humfre duce Gloucestr' et Alianora uxore ejus.
17. Item, une autre petition ovesqe une cedule a icell annexez, fuit baillez en mesme le parlement, pur Humfrey duk de Gloucestre et Alianore sa femme, les tenours dez queux \petition/ { }{ }{ } et cedule cy ensuent:
Plese hit unto the kynge oure soveraigne lorde, that of his special grace, and of the assent of his lordes spirituelx and temporelx, and of the comyns, in this present parlement beyng, to graunte to Humfrey duk of Gloucestre and Alianore his wyf, a licence to enclose .cc. acres of here lande, pasture, wode, hetthe, virses and gorste, and therof to make a park in Grenewyche; and by the same auctoritee to make toures there of stone and lyme, after the fourme and tenure of a cedule to this present bill annexed, withoute fee or fyn therof to you to be paied.
Rex omnibus ad quos etc. salutem. Sciatis quod de gratia nostra speciali, et de assensu dominorum spiritualium et temporalium, ac communitatis regni nostri Anglie, in presenti parliamento nostro existentium concessimus et licentiam dedimus, pro nobis et heredibus nostris, quantum in nobis est, carissimo avunculo nostro Humfrido duci Gloucestrie, et Alianore uxori ejus, quod ipsi ducentas acras terre, pasture, bosci, bruere et jampnorum, ipsorum ducis et ducisse apud Grenewyche, que sunt extra metas foreste, includere et parcum inde facere, et predictas ducentas acras sic inclusas, et parcum inde factum tenere et habere possint, sibi et heredibus suis imperpetuum; eo quod quadraginta acre pasture, bruere et jampnorum, de predictis ducentis acris, parcella manerii de Grenewych, quod priori et conventui domus Jeshu de Bethleem de Shene, de patronatu nostro, et fundatione carissimi domini et patris nostri domini Henrici nuper regis Anglie quinti post conquestum existentibus, in fundatione domus illius, sibi et successoribus suis, per eundem patrem nostrum datum fuit et assignatum, extiterunt, et per dictos priorem et conventum loci illius, dictis duci et ducisse et heredibus suis, in escambium pro aliis terris et tenementis, per eosdem dictis priori et conventui et successoribus suis dandis et assignandis, alienate sunt jam et concesse, non obstante. Et ulterius, de avisamento et assensu predictis, concessimus et licentiam dedimus, pro nobis et dictis heredibus nostris, quantum in nobis est, eisdem duci et ducisse, quod ipsi manerium suum sive mansionem de Grenewych, muris petra et calce includere et firmare, et muros illos kernellare, batellare et turrellare, ac quandam turrim infra parcum predictum similiter petra et calce de novo construere et edificare, et tam turrim illam sic de novo constructam, quam dictum manerium sive mansionem ut premittitur inclusum, firmatum, kernellatum, imbatellatum et turrellatum tenere possint, sibi et heredibus suis predictis imperpetuum, sine occasione vel impedimento nostri, vel heredum nostrorum, justiciariorum, escaetorum, vicecomitum, aut aliorum ballivorum seu ministrorum nostrorum, vel heredum nostrorum quorumcumque. In cujus rei testimonium, etc.
Les queux petition et cedule, leuz en le dit parlement, le sisme jour de Marcz, l'an present, et bien entenduz, del advis et assent des seignurs espirituelx et temporelx, et auxi de les communes, en mesme le parlement esteantz, fuit responduz a mesme la petition, en la forme q'ensuit:
Fiat prout petitur.
On behalf of Humphrey, duke of Gloucester, and his wife Eleanor.
17. Item, another petition with a schedule attached to it was delivered in the same parliament on behalf of Humphrey, duke of Gloucester, and his wife Eleanor, the tenors of which petition and schedule follow here:
May it please the king our sovereign lord that from his special grace, and with the assent of his lords spiritual and temporal and of the comnons assembled in this present parliament, to grant a licence to Humphrey, duke of Gloucester, and his wife Eleanor to enclose 200 acres of their land, pasture, wood, heath, thicket and gorse, and to make a park in Greenwich thereof; and by the same authority to make towers there of stone and lime according to the form and tenor of a schedule attached to this present bill, without fee or fine to be paid to you for this.
The king to all to whom etc., greeting. Know that from our special grace and with the assent of the lords spiritual and temporal and of the commons of our realm of England assembled in our present parliament we have granted and given licence for us and our heirs, in so far as we are able, to our dearest uncle Humphrey, duke of Gloucester, and his wife Eleanor that they themselves may enclose 200 acres of land, pasture, wood, heath and gorse of the duke and duchess themselves at Greenwich, which are outside the bounds of the forest, and make a park thereof, and they might hold and have the aforesaid 200 acres thus enclosed and the park made thereof to them and their heirs forever; notwithstanding that 40 acres of pasture, heath and gorse of the aforesaid 200 acres, part of the manor of Greenwich, which belonged to the prior and convent of the house of Jesus of Bethlehem of Sheen, which is of our patronage, and of the foundation of our dearest lord and father Lord Henry the fifth late king of England since the conquest, was granted and assigned by our same father, for himself and his successors, in foundation of that house, and are now alienated and granted by the said prior and convent of that place to the said duke and duchess and their heirs in exchange for other lands and tenements to be given and assigned by the same to the said prior and convent and their successors. And in addition, with the aforesaid advice and assent, we have granted and given licence for us and our said heirs, in so far as we are able, to the same duke and duchess that they themselves might enclose and fortify their manor or mansion of Greenwich with stone and lime walls, and crenellate, embattle and turret those walls, and similarly construct and build from new a certain tower in the aforesaid park with stone and lime, and hold to themselves and their aforesaid heirs forever both that tower thus newly constructed and the said manor or mansion enclosed, fortified, crenellated, embattled and turreted, without the interference or prevention of us or our heirs, justices, escheators, sheriffs, or any of our other bailiffs or officials, or those of our heirs. In witness of which, etc'.
Which petition and schedule having been read and fully heard in the said parliament on 6 March in the present year, with the advice and assent of the lords spiritual and temporal and also of the commons assembled in the same parliament, was answered to the same petition in the form which follows:
Let it be done as it is desired. (PROME)

Humphrey (Humfrey or Humphrey of Lancaster), duke of Gloucester (called Good Duke Humphrey) (1390–1447)

Humphrey (Humfrey or Humphrey of Lancaster), duke of Gloucester (called Good Duke Humphrey) (1390–1447), prince, soldier, and literary patron, was the youngest son of Henry, earl of Derby, later Henry IV, and his first wife, Mary de Bohun (d. 1394). He was protector of England during Henry VI's minority and the first English patron of Italian humanism.
He and his wife successfully petitioned on 6 March for the right to make a park at Greenwich and to build a crenellated house there. On the last day of the parliament, in their preamble to the grant of the lay subsidy, the commons also commended the actions of the duke in the previous year in dealing with the Burgundian threat to Calais, their own anti-Burgundian and anti-Flemish feeling being revealed by their praise for the fact that Gloucester had impounded the men, goods and property of the enemy. All of this might suggest that Duke Humphrey was in the ascendant, yet it must be remembered that he had had to petition long and hard to ensure adequate financing for Calais. The commons might still regard him as something of a hero, especially as their own commercial interests made them anti-Flemish in outlook. But the solution to the problematic financing of Calais was not long lasting and by 8 January 1438 the duke had seen fit to resign his command. Moreover, the commons in 1437 followed their thanks to the duke with similar thanks to Cardinal Beaufort for his 'immense goodwill', and to the chancellor, treasurer and other lords for their counsel to the king, especially towards the maintenance of justice. Thus Gloucester's position was enhanced by the parliament but not at the expense of others. The commons' vote of thanks emphasises the apparent political unity of these days. (Curry)

Biographical source include;

G. L. Harriss, 2004, ‘Humphrey , duke of Gloucester (1390–1447)’ Oxford Dictionary of National Biography (Oxford University Press) online copy (subscription may be needed)
Curry, A. (ed), 2005, 'Henry VI, 1437 May Introduction', in The Parliament Rolls of Medieval England, ed. C. Given-Wilson et al., Internet version, at [online copy > http://www.sd-editions.com/PROME (Scholarly Digital Editions, Leicester)