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Thought I'd post an update (as though anyone is the least bit interested)...
Today (just 2 weeks + 2 days after I sent them) I received my identification documents in the post, together with the cheque that I sent and the licence should appear within the next 10 days. Hurrah.
So it seems I was wrong about the money - the earlier link and also the application form itself seemed quite explicit that £20 would be the cost. Maybe I'm a slightly special case in that I sent the licence off for a change of address 9 years ago, and only did that because it was a useful form of id (haven't driven since the 1980s). When they sent back an application form requiring photo and proof of id because of the change of format, I just couldn't be bothered and so the licence has been languishing at the DVLA alll those years; having the licence back in my possession could be advantageous in my present circumstances which is why I decided to apply for it again.