1287 is a bit late (about 90 years) for the traditional dating of RHAHMM to the time of Richard I and King John. What we get down to is the merging of lots of stories with garbled snippets of actual events- hence Robin having such a wide range, from Kirklees through Loxley and Barnsdale to Sherwood and Derbyshire, and that's not counting the claims for even further afield.

Is this alleged BBC fratriphobia just one more myth to add?

By the way, it's Richard's 907th deathday on Thursday.