Well, thanks for the enthusiasm folks, but some bad news follows.
I had a call from the same agency (different person) the following week, saying I had been recommended for another job. "But", I said, "I already have a job with you, I'm starting in June". Well, the chap went away briefly, and was surprised to learn I had not been told that the job I'd been offered had now been given to someone else internally. Bastards.
So anyway, I'm happily working at installing EPOS equipment for the next few weeks. Next contract should be something more serious - looking forward to getting my security clearance! Has to be better than being based in an office doing 2LS work anyway...