The Wickes 216980 may be close. The length is specd at 17.3 cm. As with a lot of this sort of thing its hard to tell from that and the picture.
Thanks JimCrow (and all).
I have an Armitage Shanks toilet that must have been installed in the 1970's.
The flushing handle/bearing has worn but I've "fixed" it with some plastic strip and it seems to work ok for now.
I'd like to replace the handle assembly but I'm having difficulty finding one that would definately do...