I've finally accepted the fact that my rather nice Planet X Sportive Ti is a bit small for me. The riser stem and yard of seatpost should have been a clue.
The opportunity looks like it has arisen to acquire a 2010 Roubaix S-Works SL2 frame in a suitable size. I know they're good, and it seems to be a truism that most middle aged blokes on Tarmacs would be better off on a Roubaix. It just seems a bit of an old man's bike with its Zerts inserts and stuff. Am I being a dick?