BT Master Socket

[#1]

On this house there is no master socket - a cable comes up out of the ground and is hard wired into normal telephone extension cable which then disappears into the house. Inside there is a very old looking hard wired junction box and then elsewhere in the house two extension sockets. I want to put in new wiring to make sure I get the best signal, but where do I wire from? Do BT/Plusnet have to provide a master socket? Or does their responsibility end outside at the first connection?

[#2]

If you had a fault of some sort on the phone line BT Openreach would almost certainly install a modern NTE5A master socket as part of fixing it.
Unless your wiring is the result of some amateur extension work in the past it just sounds like an "old school" GPO install that's never been updated in some decades.
One of your sockets could well be an old-type master in reality (look inside them) but nonetheless they all probably belong to BT and you shouldn't be touching them. 

[#3]

So in that case all the wiring inside the house is the responsibility of BT/Plusnet? And if there's an internal fault which is affecting my broadband then they must come and deal with it FOC?

[#4]

Possibly. There's always damage which is your responsibility so a charge could be levied......
Also, if there's an internal problem they may just install a new master socket and isolate the internal wiring, which may or may not be convenient.

[#5]

I was told by an uncle about one BT engineer who,  when visiting his house to fit extension wiring for him ( yes, he paid BT to do it  :o), left without fitting an NTE5(A) MJU where there was previously just a non-faceplate termination box for the incoming cable. So, yes, it is possible that they will not fit one 
I'd like to know whether a BT engineer, when replacing an CTE5/NTE5(A) faceplate MJU, MUST replace it with another NTE5(A) MJU  or better ( e.g. filtered faceplate NTE200x) ?

[#6]

Thanks for all that .. not sure now how to proceed. How do I get Plusnet to send out an engineer to fit a master socket of any type?

[#7]

get FTTC, they install one if you haven't got one (as with me)

[#8]

Ah well, Tony, I wish I could!
FTTC doesn't seem to be even a remote possibility on my exchange!

[#9]

I think BT will charge (£90?) if they are not fixing a fault