As I mentioned in the acquisition thread, the initial mark on the half groats appears to be lis over a full rose and not a half rose as quoted by Spink and Seaby.
Potter and Winstanley quote the type I mintmarks as Halved Sun and Rose, Halved Lis and Rose, Lis on Rose, Lis on Sun and Rose, Lis, Cross Fitchee and Rose.
The halfpenny also appears to possibly be lis over a full rose and not Lis on half rose or Lis and Rose dimidiated. Is this time to reappraise the early initial marks as listed in Coins of England?
A full corpus of the known halfgroats is shown below. The top row is obverse 1, the bottom row obverse 2. The top left coin is the one with a Richard III reverse, the bottom left coin is the best known of those available, ex Cuff 946, Martin 135, Murchison 111, Shepherd 198, Montagu 674, Lord Kesteven 29, Murdoch 391, Walters 493, Lawrence 679, Carlyon-Britton, Norweb 305 and Shuttlewood 36. I don't know where it is at present.