The line extends for another 3km beyond us. Total lime length 5km.

We wanted to swop to a closer cabinet but that would have still meant that some customers would have been 4km from the cabinet we wanted to transfer to. Any changes to the layout of our service would still have left customers at the furthest distance from the cabinet below the 2Mbps USC. Openreach said that this was not acceptable.

So just under 2km - 33dB is in the right ball park for that distance and it should give around 12-13 Mbps on attenuation or about 15 on distance. However there are a lot of factors that can affect that part - gauge of copper, actual underground routes, link from FTTC cab to PCP distance ...

So, your speed of 8Mbps is little low and I would suggest that the cause of that is high levels of noise. Overhead is more susceptible than buried and as I mentioned before overhead power and transformers can also have an adverse effect.

you could have asked openreach about co-funding a cab closer to you

I gave up on Openreach and BDUK. Nothing positive will be done in our area the infrastructure is very poor and badly arranged with multiple cabinets and exchanges serving a large area beyond the reach of FTTC. The ducting is terracotta pipes under the old shingle surface down narrow sunken tree lined lanes.
We do however have one big asset overlooking us - The South Downs.
Hopefully in the next few months we will have a Fixed Wireless service up and running.

I think they will look at it. Just being on an FTTC enabled cabinet doesn't mean the service is acceptable. However, a warning, it will not be cheap.

A generalisation of what is possible for a not so remote community, of say 24 houses, to improve their speed would be nice to know. Their have been reported instances of DIY fibre laying to improve local services but how it is all connected up, and by whom, is never mentioned.

Enquires to BT only seem to indicate part funding a local cabinet for eye watering sums of money or perhaps sharing a leased line but even then, the monthly fee for anything decent would run into several hundred pounds for each user per month.

Being stuck on around 5Mbps is only just acceptable for 2015 but a modest increase to 30Mbps would open up very many more opportunities to experience the internet without frustrations.

Wireless connectivity solutions might be wishful thinking particularly if you are in a no service area. So is the OP stuck with what he has now for perhaps many years to come, if ever?

Down here in Bath, there is a tiny village Claverton,about 70 houses, they paid to have fibre installed,ducting, overhead fibre & cabinets,cost was around £48000.

http://www.clavertonpc.org/images/stories/minutes/23...

http://www.btplc.com/BTToday/NewsList/Villagecofunds...

http://www.ispreview.co.uk/index.php/2015/05/tiny-so...

Somebody at the local council running the BDUK project will have an email address for a BTO person you can contact in your area, or at least responsible for such work in your area.