Hi,
Thank you to everybody who has commented thus far. I have had my DSLR 450D for a month (my first). It came with no lens as I plan to have a proper crack at Astrophotography (sadly just camera to eyepiece thus far).
Then I thought I'd get a lens so that I had one. It became clear that it was far cheaper to get an EOS film camera with a lens on eBay (with autofocus) than a lens. I struck lucky with an EOS 300 winning the bid at £6.50 that came with a Centon flash gun (which works on mycamera), a Canon AF 28 - 80m - what I was after and this big Sigma lens.
Those of you who said M42 I now know were spot on as theT2 only got half way and was certainly not up to the job even with the tripod mounting ring to put the lens directly on a tripod.
As the last reply noted the T2 does not depress the aperture pin.
However, I have now ordered a flanged M42 which should work ok.