Who was Humphrey Percival?

Yesterday whilst rebel-hunting I stumbled on the story that Buckingham had sent his most trusted friend, Humphrey Percival, to York to meet Richard after Edward's death. I'm not quite sure where it originates, More?

It would be very interesting to know who he is. Why? Because as Stephen knows, two lots of Percivals occur in Stillington's story. One is a Jenet Percival of Ripon, who in some genealogies is married to his brother or father - both unlikely. The other Percivals are from Eastbury in Somerset and one of them is married Katherine Hampton, the aunt of the Bishop's grandchildren (sorry!). They are also related to the Newtons - in fact one version has a Percival marrying Joan Cheddar/Talbot - Eleanor B's sister in law.

If our Humphrey is indeed related to them then there is a possibility that either through them or Stillington himself he would be 'in the know'. And this would give Buckingham the chance to effectively make himself kingmaker - something he'd find very appealing.

I've not found a single mention of Humphrey elsewhere so far - but there are so many variations on the name. The other Percivals I've turned up are from Kent (but no Humphrey) and Sir John Percival, Mayor of London in HT's time, who came from Macclesfield, but his son was Richard. However, Ralph Percival the younger from Eastbury was killed a Bosworth. I'm not sure what side he was fighting on - he doesn't appear in the normal lists. Can anyone help? H