Quite what Robinson source actually was is not really clear. He may have seen the genuine rolls of parchment or he may be referring to one of the early printed calendars of rolls or to some other source. There are also some other problems with the citation as the 29th regnal year of Henry VI was in 1450-51. However, while the 1460 licence is well documented in the 'modern' Calendars (Actually in Lyte, H.C. Maxwell (ed), 1927, Calendar of Charter Rolls
Vol. 6 p. 137), Gatehouse
can not find anything like a licence to crenellate for 1449, 1450, 1451 and certainly not for Richard Beauchamp (who was a boy of 14-16 during these years) in searches of the early calendars like Rymer's Foedera
and the more recent and generally well accepted Record Commission calendars of Patent Rolls and Charter Rolls. However the original rolls at The National Archive have not been examined. There were some records of royal business which, although the business enrolled relating to England, were enrolled while the King was in Ireland. These were part of the rolls stored at Dublin which are now all lost but Robinson citation of Rot. Turr.
(Rolls from the Tower of London) would exclude this tiny handful of possibly lost records. All one can really say is the only reference to a licence to crenellate Bronsil in 1449 occurs in Robinson, the citation is unclear and, at best, is typographical inaccurate. No such licence occurs in printed calendars usually accepted as a reliable source. Richard was a child in 1449 making it unlikely he was granted such a licence.