Inside my 2nd hand copy of Grimwade's there was an interesting surprise....
A thank you letter for the recipients help in I assume completion/research for the book. There was a name sticker on the inside cover and I believe the owner previously worked for Goldsmiths Hall which would explain them being in a position to help. Also in the top corner is a pencilled 8 suggesting that maybe Mr Grimwade unsurprisingly had lots of people to thank on completing his Wonderful work!
All the best,