This is exactly what I did. I needed the cable to run outside so bought some external cat5e from a local shop, and a crimp tool & connectors from amazon. The thicker external cable is probably meant to connect to the rear of a socket rather than crimped connectors but it's been working fine for the past 4 years

As you say, a simple job to re-site the MS & what's the comeback? Not a criminal offence & OR are unlikely to discover the move. It's certainly a better solution but how much improvement in line quality would result?

In reply to a post by DavidA23:

As you say, a simple job to re-site the MS & what's the comeback? Not a criminal offence

Actually, it is.
See the Telecommunications Act 1984 and the Communications Act 2003

In reply to a post by deniscampbell:

You can buy low loss shielded, twisted-pair cable with RJ11 ends. Effectively the same as an RJ45 cable.
The cable from cabinet to house is probably just bog standard telephone cable, but is not be as subject to mains borne interference as the master socket to router, so better quality cable may help.

Indeed you ~can~ buy that. But what practical use is the shielding? I'm not aware of any domestic market kit that provides an "earth" connection for a shielded RJ11 cable. AFAIK a shielded cable run should have the shield connected to "earth" at one end only in order to avoid problems where the "earths" of the devices at each end are differently terminated (e.g. on different phases or locally grounded rather than using a common supplier provided earth).

Genuine question there, not trying to be a pain! My knowledge is only partial in this area so am happy to be educated

In reply to a post by MrSaffron:

Given Ethernet switches are now down in the £10 to £15 region e.g. Netgear 5 port at £12 then going for modem and router at point of entry and Ethernet running to a remote switch is only the price of 3 pints.

In 1992 the Kalpana EPS-700 7 port switch had what I presume was a list price of $10,995. It was $1,000 less a couple of years earlier.

Well, not being proficient in legalese I've little or no idea what that says.
Several years ago in another house I moved a master socket from the downstairs hall to a bedroom. A couple of years later we suffered a large lightning strike which blew up our phone & my PC. BT (as it was then) came round and rewired the telephone circuit & in passing asked: "How come your telephone cable enters the house via an upstairs window rather than downstairs?" I said I had no idea - it'd been like that since I moved in. That was that - nothing more said.
Of course, I understand that you or others on this forum wouldn't advocate breaking the law so I guess it's a case of: 'I takes my chances...'
I just wonder whether the possible line improvement is worth the hassle.