Thanks for that Rob and Kal, I am only just starting to research Henry VII, hadn't realised what a fascinating king he was until recently!
During my first hour of on-line initial research I saw tentative issues mentioned, wondered what the term meant, saw some for auction, and formed a very possibly inaccurate early conclusion that they can't be that rare.
Here is one described as 'tentative' sold at St James earlier this month, is it correctly attributed?
http://www.the-saleroom.com/en-gb/auction-catalogues/st-jamess-auctions-knightsbridge-coins/catalogue-id-srstja10011/lot-c933c260-56ec-45eb-bb31-a58500bb7471