Joining Plastic Waste pipe to Lead pipe

I'd bung a bit of silicone in there too!

Christian.

I think you'll find the ID of the nominal 50mm muPVC pipe is about 56mm. That would jam down rather well into the lead. A bit of silicone grease could help it its way. Sparky tape around the outside and a very large jubilee clip should just about smake it indestructable.

screwdriver

Ernie: Are you going to just sit there and annoy me or are you going to read your newspaper? Eric: I can do both!

Er, yes it is a bodge, but it might still give you a reliable water-tight joint :-)

I'd be inclined to go for silicone or gripfill rather than hemp & mait to get some mechanical grip to the joint, and I'd perhaps try slitting a short length of plastic pipe and slipping (and solvent-welding it) over your main plastic pipe to try to make a tight fit into the lead with a bit of silicone or whatever to just fill the gaps. Incidentally is the 40mm pipe you're using push-fit or solvent weld (PP or ABS)? If the former you'd find solvent weld would be a better fit as it's slightly larger diameter.

A more pukka way would be if a 50mm plastic compression joint made a good connection with the lead (depends not just on diameter but also if the lead is circular enough).