A range is 8.3 - 4.6.
I haven't spoken to the neighbours. Most are elderly and not into hi speed internet, although I suspect that my immediate neighbour may have a higher speed, so I need to chat to him.
I agree that FTTC may well be worth a punt with BT. It surely can't be worse, but I'll see what Openreach come up with on my ADSL complaint first.

BT Consumer won't sell you Infinity 1 with those ranges, but a Faster Broadband which is same technically but generally without all the nice offers...

So look at others such as Sky, PlusNet, Vodafone.

1 month contracts should appear more widely soon so taking a risk becomes less of an issue.

Just been for a wander. Half my cul de sac are, like me, on PCP 5. The other half are on PCP 18. I now realise that 18 is only half as far away as 5. I appreciate that is only half the story, and of no help to me, but it just adds to that 3rd rate citizen feeling.

Looks like I'll be changing ISP soon then, and still get less than 10Mbps. I stayed in a B&B near Lands End last week. Middle of nowhere, and miles from anywhere, but 30Mbps. Slightly envious.

What does the Openreach site say?

The Openreach site says FTTC may be available, and has probably said that since 2010.
Had a look at all the house numbers on the DSL checker:
1-7 PCP 18, and VDSL up to 20Mbps
8-20 PCP 5, and VDSL varying between up to 3Mbps and up to 5Mbps. Mine is in this bunch, and has gone down from 'up to 8Mbps' a few days ago to join the 'up to 5Mbps' team.
Some of the properties at 21 and higher are PCP 5 poor relations, but a few are PCP 18, at up to 40Mbps.
Most of the properties are over 30 years old, but I suspect that the high speed PCP 18 ones are individual new builds

Have now had a visit from a very helpful Openreach engineer. The line length from cab 5 to me is 1500m, but there is another cab (5/2) in between, which is a 600m line length from me. At first he was hoping that 5/2 was actually cab 18, which has FFTC. Unfortunately, cab 5/2 is not 18 in disguise, has no fibre, and is just an extension from 5.
Nevertheless, he found a better connection was available at 5/2 than the one I was on, and that change has boosted the signal at the modem to 3.8 Mbps. I only get 2.6 Mbps after the router, but that is a huge improvement from 0.7.
Now that the copper connection has been improved I will push TalkTalk to offer me a fibre option. If they won�t, I�ll try BT. Even 5-8 Mbps FTTC would be worth the swap.

Cabs with a / in the name are always a pillar or sub cabinet.

One or two have been converted into full cabinets with fibre twins but relies on the economics and where the BDUK roll-out is in terms of helping the edge cases

Thanks Andrew, I just wish they had thought this through when the fibre was put in in 2010.
In both geographic and line terms, it is more or less a straight line from Cab 5 to the far end of our road (confirmed by the Openreach engineer). Cab 5 is at the far end of the chain, cab 5/2 is at the end of our minor road nearest to cab 5, and I am in the middle of our road . Cab 18 is midway between 5 & 5/2 and is on the same straight road.
The houses nearest the cabs are on 18 and can get 40Mbps fibre, the middle bunch (me) are on 5 and get poor ADSL, and the furthest houses from the cabs are on 18 and get 20Mbps fibre.
I know I can�t change that arrangement, but it defies common sense.
Anyhow, my ADSL is now better than it was, so I�m grateful for small mercies.

To close this thread:
TalkTalk wouldn�t offer me a FTTC service, so I went with Plusnet.
The new service was connected yesterday and is giving over 5mbs up, and about 1Mbps down. Not brilliant, but as expected, and double the ADSL speed.
For simplicity I am currently connected via the Plusnet router, but will re-instate my Draytek modem and Apple router later today.