Thanks all - tried runbritain, and did find the ealing mile, but not easy to get to on a fri afternoon if you're not in London.
I did look at the BMC - there is one near me in May that has a vets category - does anyone know how it would be for someone of about 6 min mile standard? - I don't want to be laughed out of there.
I will also try the BMAF/SWVAC. I am running in the Avon League later this summer, but only 1500, no mile, and I really wanted the proper mile this year, ideally with some feel of commemoration of the Bannister mile.