In reply to Blue Straggler:
Talking to myself as usual
This now looks like a choice between:
Canon 100mm f/2.0
Canon 100mm f/2.8 macro (not the expensive L glass - the cheaper one)
Tokina 100mm f/2.8 macro
All roughly the same price depending on bits of blah blah (London Camera Exchange has used versions of both Canons at £240ish; I have not seen a used Tokina but it's £330 new on Amazon, as a guideline)
Anyone know anything about these three? None has image stabilisation, that's fine by me. The slightly slower ones may be more fun and versatile with their macro capability; I wonder if I will miss that extra stop though, both for DoF control and sheer speed. The Tokina front element is recessed like on my 50mm prime, I like this (reduces flare and lends some protection).
Primes any longer than these are simply way out of budget.