connecting metric to imperial pipe

[golffury]

Hi, Can any one tell me the best and most permanant way to connect a 2" solvent pipe to a 40mm solvent pipe? I have a kitchen macerator unit connected to a heavy duty non return valve. At present I am using flexible rubber connectors and hose clips but you can see them expanding and contracting and I don't like the look of it.
Any suggestions?

 

[spraggo]

http://www.koilogic.co.uk/store/go/category/5/122

 

[dcawkwell]

Why not replace the 2inch with 50mm pipe?