Can anyone recognise this diverter?

[Corazones]

I would like to identify this old bath/shower diverter so that I can obtain the correct washer and maybe an exploded diagram before tackling the rather awkward job.
To explain how it operates, the upright piece on the left is the hand shower, its hose (and connection to the diverter) pulls up to use it, being inconveniently connected to the valve below the top of the bath. The spout on the right fills the bath according to the position of the small lever at its base.

I have looked right through the entire Google library of "shower diverter" images but cannot find anything like it!
If it cannot be identified, any suggestions for replacing the (presumably perished) washer, and what to order in advance, would be greatly appreciated. Fortunately the bath panel can be easily unscrewed, but the diverter is in a very awkward place.
There is no brand name anywhere on the chrome. The main shower is by Osma, but some other fittings in the house apparently came from Howdens. One of the bath taps marked "HB" can be seen on the left.
Many thanks,
Alec.

 

[Nige F]

2 places in E sx. The plumber's mate Firle road Eastbourne ( and on the 'net ) Metamorphosis on the A22 Lower Dicker near Boship roundabout. I doubt if it'll just be a washer or O ring

 

[Corazones]

Thanks Nige, but they're a bit outside my area. The only plumber's merchant anywhere near me is Plumbase at Liphook, but yes, you have given me an idea and it's worth giving them a try. Not too hopeful, though....

 

[AGAS]

The plumber's mate Firle road Eastbourne ( and on the 'net ) Metamorphosis on the A22 Lower Dicker near Boship roundabout. I doubt if it'll just be a washer or O ring

Thanks Nige, but they're a bit outside my area. The only plumber's merchant anywhere near me is Plumbase at Liphook, but yes, you have given me an idea and it's worth giving them a try. Not too hopeful, though....

the net is your friend and to top it off he's given you an address as well , maybe nige should find somewhere closer to you

 

[Nige F]

Liphook - is that Hampshire ?

 

[JohnD]

did you try Lunns?

 

[Corazones]

Yes, Nige, Liphook in Hampshire. And AGAS was right about the web being your friend, I had a reply from Plumbase straight away identifying it as coming from Heritage Bathrooms, possibly the old "Shaker" style. They're finding out more and hopefully a diagram.
They did however point out that the bath will probably need to be removed, and I can see that they're right. The bath sides are completely vertical and very tight to the wall, and the bath has obviously been tiled in place. It will obviously be "one of those jobs" which may have to wait a while!

 

[Corazones]

Finally, some good news. And some more good news.
For one thing, I have discovered that the taps end of the bath is against a studwork wall which forms one side of a cupboard, with access cut out of it.
Secondly, I thought I would give the sticking valve a good spray of silicone lubricant from an aerosol. Hey presto, full movement was restored and the leak cured!
Thanks for everyone's help. Thread now closed!