Thanks Sudokulover for your kind attempt at help. I had actually noted the fact that T is the 20th letter, but the way forward remains shrouded in gloom for my weak eyes...
Daniel, I'm obviously having a thicker day than usual. I got the alphabet and numbers connection and I've got 4dn but still stuck. Are the entries real words?
Oh, and thanks as usual, despite my current fog I look forward to the Speccie.