Washing machine wastepipe dilemma

[cream69]

Recently we replaced a washing machine
but was wondering how we can connect
the new washing machine waste pipe to the pre-existing
sink plumbing installation.
The connection from the old installation has a kind of screw fit
yet the waste pipe from the the washing machine is smaller and has
a flat end.

The one on the left is the pre-existing connection.
One on the the right is the new washing machine waste pipe.

This is the old pre-existing setup which the screw fit in the previous
picture is connected to.

Do we buy an adapter or some kind of clamp or do we need to change the existing plumbing set up?

 

[seco services]

by looking at your pic thats the flexi hose your holding.
next to your hand is the non return valve that should screw into the part on the bottom pic with the rag stuck in the end.

then the flexi should fit onto the non return valve if all parts are there.

or if all the parts are not there then fit a new trap with a w/m outlet