The engineer has been (on Wednesday) and he wasn't particularly helpful - so I'm left with four possible solutions:
1. Run a LAN cable between the router and the study where everything else lives (possible but not very domestically acceptable)
2. Fiddle about with phone socket wiring (sounds dodgy even if it works)
3. Use home plugs using the mains wiring as LAN cable, which is what I'm doing at the moment (works very well but disappointingly slow - I get speedtest of 71.3Mbps down at the router but only about 20 at the far end of the homeplugs, even though they're supposedly rated at 500Mbps - here - http://www.solwise.co.uk/net-powerline-500av-index.htm
4. Go wifi, which is what I've decided to do, using this http://www.tp-link.com/en/products/details/?model=TL...