I had considered something along those lines but it really is very loose, to the point that it will distort and I don't imagine it would make a good seal.
A while back I had to extend my mum's washing machine waste. We picked up an extension kit from screwfix. The connection was very loose. I ended up using CT1 to make the seal water tight and clips to prevent it pulling apart. After 2 years it seems to be OK.
One reflection, had I known beforehand, I would have ordered a better quality product. The Scewfix one is rubbish.
Thanks for your replies. I ended up with an extension kit from screwfix, cut and removed part of the rubber on the waste pipe attached to the washing machine and then used jubilee clips to hold it all together. It didn't leak and I am sure it will be fine.