Old style plastic pipe problem

I'm new here, so hello to everyone.

We are in the process of removing our old 1970's bathroom suite and have come up against a bit of a headache. After removing the old plastic cistern, we have realised that the cold water feed pipe, along with the rest of the cold water pipes in the bathroom ( and downstairs toilet ) are not the usual.

Having talked to a variety of plumb centres it turns out that this grey pipe was used up until about mid 1970's. It is not 15mm, or 22mm, or 1/2" but closer to 17mm. And nobody seems to stock anything that we can attatch to it.

Our idea was to try and find a convertor to 15mm, use standard 15mm plastic pipe, and place a valve inline so that we can shut the supply off in the future should we wish, but
nothing seems to be out there that will do the job.

We currently have the cold water supply turned off but this means we are unable to flush the toilet downstairs and have to keep relying on pouring a bucket of water down to help flush it through .. not an ideal situation.

Does anyone on here have any advice on this, or have you dealt wit this pipe before ? We really dont want to rip the whole pipe line out ... we are on a budget which is why we are doing alot of the work ourselves. It's just this grey plastic pipe that is causing major problems.
Cheers for any help

Daz

have you tried a 15mm olive on it yet to see if it is 17mm what name is on the pipe i.e hunter

Havent tried an olive but it will fit snugly inside a plastic 22mm pipe. A 15mm pipe insert is to small and a 22mm pipe insert is too big.

Can you see any writing on the pipe, like ABS

I came across some weird plastic pipe once in wigan. I shat it as had never seen it before so what i did was tried a 22mm olive on it which was too small so i rasped down the plastic until it fitted and used plenty of PTFE and put a 22mm compression on it and then from then used 22mm copper etc..

But the wall was thick enough to file down to a smaller diameter etc..

It'll be Poly-york plastic. It came in imperial sizes 3/8" 1/2" and 3/4".
You'll have trouble getting anything to fit but if you can get back to 1/2" polyyork internal diameter a conversion ring for imperial copper to metric fittings will fit over the pipe. Wrap some ptfe round and tighten up the fitting then you can go off on whatever type on metric pipe you want.

Thanks for all the info. When you say get back to 1/2" do you mean just sand /rub it back until it reduces to that size ?

It's so annoying that nothing will fit to it, so hopefully going with the advice on here something will work.

A "Philmac" universal coupling will work