Identifying ridge tile

Have a single ridge tile to replace, cant find anything suitable in local merchants so will prob have to ring around.
How does one describe* a ridge tile? Dims are approx 240mm wide, 120mm high, can't remember length but it will need cutting down anyway as the missing one is shorter than the others. local places only had slightly wider and flatter ridge pieces. Plain clay tiled roof.

Frustratingly, Selco do a chimney pot with a bonnet top, the bonnet being the correct size! I'm not forking out all that just to cut the bonnet off and bin the chimney


*I appreciate that I have just asked how to descibe a ridge tile followed by me describing it, but if anyone can help out anyway...

Generally the ridge come from the same manufacturer as the tiles so if the manufacturer's name is stamped on the back of the tiles it will be a starting point.

Found one in a local BM that is also a reclamation yard.
69p, happy days!

Thanks for the tip though, I'll remember that for future reference.