In reply to a post by cantoris:

When I move in and want to get BT Infinity ordered, what would be the quickest way to ensure it can all get sorted - preferably in one visit?

When ordering the service, just state that there is currently no master socket and that an Openreach technician's visit will be required "to normalise the wiring and to fit an NTE5/C with SSFP".

Thanks. Sounds like one to order over the phone rather than via a one size fits all webform!

Just for completion, here's a photo of the socket in the front room as viewed from outside:
https://gyazo.com/f199285e853af63dbeb8659de2fe7ffd
The double-glazing shows the scale.

The other socket in the house is similar. Both have wiring on the outside of the house going back into the porch where the grey junction box thing is.

In reply to a post by cantoris:

Just for completion, here's a photo of the socket in the front room as viewed from outside:
https://gyazo.com/f199285e853af63dbeb8659de2fe7ffd
The double-glazing shows the scale.

The other socket in the house is similar. Both have wiring on the outside of the house going back into the porch where the grey junction box thing is.

I can't see anything through that window - do you have anything clearer?

Can see a single phone socket in a perhaps 40mm x 40mm surface mount box

I can only photograph it from outside as I don't own the house yet.

Here's a highlighted version:
https://gyazo.com/cfc8450b31c619c2befe3572404bc402

Looking at that, it does look similar in size to the small BT sockets that have been used in the past. They were dual purpose and a module could be inserted to change it from a Secondary to a Master.

That appears to be an old LJU and if both sockets are LJUs then you would require the services of an Openreach technician.

That could be a master we would need to see pics inside.

One of them is probably the master.

There are masters in the same size as those - I still have a few here, so one could be a master. Seeing close up images of each along with the insides will soon say one way or the other and at present it is impossible to say if there is a master or not.