Perhaps if you prioritize getting the router stats from the test socket and recording them before getting involved with the extension wiring from the faceplate that might be a good first step - if the line is underperforming is always a good thing to have some results from the test socket before contacting an ISP.

Hi 4M2,
Here are the stats router plugged into front of master socket, on filter with phone etc.as it had been for nearly 8 days.

Connection Speed Down 1020 kbps, Up 606 kbps
Line Attenuation 47.5db 29.5db
Noise Margin 1.9db 12.3db

Stats now plugged into test socket on a dangle filter, no phones just the router

Connection Speed Down 1020 kbps, Up 606 kbps
Line Attenuation 47.0db 29.3db
Noise Margin 4.9db 15.9db

After I connected it up like this I did a factory default restart as sync speed hadn't improved, this made no difference. So things are as the above.
Speed test results 0.88 Mbps downspeed, 0.51 Mbps upspeed

still v. poor then

so any phone sockets work when the master faceplate is off ?

should be 4 times the speed

Sky may have capped the line speed via their dlm system and spare noise margin is often not visible due to power back off techniques.

In which case its get the wiring as good as it can be and wait for things to improve and their dlm sometimes does this automatically or phone sky and ask for a reprofile

a noise margin of 5 ??

seems a bit aggressive for power saving

Sorry to hear that, I thought the slow speeds that you reported in your opening post might be due to more than a ring wire issue alone.

Can you try a different router, adsl lead and micro filter in the test socket sometime?

Phil, neither of the phone sockets worked with the master faceplate off, those being the master socket front and LJU in the living room.

I've had to come away now, so put it all back as was, router in master socket but not in the test socket, phone back in etc. Haven't done any wiring removals, try another day I think.

I think Andrew is right my mate needs to get on the phone to Sky for a reprofile.

I'm across the road and get 5.18 down and 0.38 up with EE Adsl Max, so my mate should be getting something similar for down speed, his up is better than mine though.

4M2 I did try a quiet line test before from a corded phone on a micro filter in the test socket, and it came back as excellent line quality, mos 4.5 So I don't think there is a fault on the line, bit of noise margin difference master socket & test socket, but I didn't get an improved sync speed in the test socket, which I thought it would have done.
I did try one other micro filter he had around the house, but had no connection, so must have been a dud, so put the previous one back in. I think I have an old unused adsl lead, micro filter yes, different router, don't think so...think he binned his previous one. I have my old Livebox router but that was with Orange, would it work with his broadband being Sky? That may be a silly question, but I've no idea.

Probably best for your mate to contact the ISP and tell them that the sync speed is unacceptable when checked from the test socket and that a quiet line test was done with perfect results.

What the ISP will do about it is anybodies guess though...

Yes I think we'll give that a try next. I'm sure there are things they can do there end. He did ring once, the things they mentioned about doing, cleaning cache, cookies, browsing history, another phone on the line, moving it to the master socket all done with no improvement, in fact before I left with having done 3 restarts, the down sync speed actually dropped a fraction! I think they mentioned about sending him a new router, but I don't think there is anything wrong with it, the issue is exchange side I feel.