Had to replace cistern valve. The original ball c*ck arm had a copper and this had been bent into an 's' shape to go around the syphon box but new one was straigt hard plastic so the answer was a Torbeck of which Ihad never heardof before.
Anyway the 'Torbeck' I got still collides with the syphon so I twisted it off the vertical to clear the syphon. It now appears to be working fine but will this affect the satisfactory runib of the valve ?