Toilet flush thingy

[MikeRC]

Hi....the toilet kept flushing of it's own accord so I unscrewed the big plastic thing in the middle of the toilet tank.
Mine screws straight into the pot but the local plumbers merchants only have something different.
I shouldn't think it has to be exactly the same but it must screw in.

Can you please tell me where I should be looking ?
What do they call this thing ?

...any help appreciated.....Mike

 

[Alastairreid]

a syphon valve!

have you tried B+Q?

 

[Tipper]

Loads a bits here!

http://www.lunns.net/

 

[MikeRC]

...thanks people...got one that fit...all fixed.

....Mike