Average speed now 10Mbps less than May this year. What could have caused this?

[#1]

Quote from: Terranova667

Vectoring is Mandatory for Gfast it doesn't work without it so Openreach would have to roll Vectoring out at some point either before or at the same time as Gfast.

No, they won't. Not in the sense of 'adding it to FTTC' anyway. Vectoring calculations are performed by the DSLAM and the whole point of G.FAST is that it will use new DSLAMs located closer to the end-user. I don't know if they intend to phase out FTTC or run it alongside G.FAST but either way there is no requirement for vectoring to be rolled out across the current FTTC network. BT have said they might do it in a few BDUK areas where it will significantly increase the reach but basically FTTC is pretty much done now.
So really it's two different things:
FTTC (pretty much as we know it now)
G.FAST (which will include vectoring technology).
The two are as separate as ADSL is.

[#2]

I worked closely with BT on numerous site to site Kilostream links in the mid 80's, ISDN in the mid 90's & recently FTTP.
My initial impression from those early days of BT has not changed. The Installation teams cannot deliver what the salesmen promise.
I've probably installed miles of Cat5/6 cabling but not all around the skirting board.
DM

[#3]

It doesn't sound like you were involved in FTTC otherwise you wouldn't have made the comment about BT not predicting crosstalk issues. In fact I have real doubts about your technical competence given that you appear to be sarcastically dismissing the whole idea of crosstalk in your first post in this thread. No-one who knows anything about FTTC or EM characteristics of wires would be so dismissive. Everyone involved in the development of FTTC (which very much includes BT at Adastral Park) has known for a long time (from the start really) that crosstalk was a signficant risk.
But BT is a business and has to deal with the real world. Whether the limitations and hindrances are technical, financial or political or from third parties or their own ineptitude (and I've been involved in installing a leased line and helping looking after long and flaky telephone lines so I know what a bunch of muppets they can be). The fact is that they have to make compromises. They decided that vectoring from the start was likely to be more of a hindrance than it was worth and have now concluded that it's either really not that wonderful or (more likely) that they have to pull their finger out and go to G.FAST instead of trying to beat the dead (or at least quite poorly) technology of FTTC.
I for one am glad about that. As I wrote previously I wish they'd just go for FTTP but it seems like everyone else agrees that G.FAST plus a leaner, meaner FTTPoD is the best way to go.
http://blog.thinkbroadband.com/2014/10/g-fast-shows-copper-is-still-an-option/

[#4]

You're right, My involvement with FTTC is purely as a home user.
DM

[#5]

Quote from: Champnet

I...he Installation teams cannot deliver what the salesmen promise.... DM

Derailing my own thread temporarily, I just have to relate a tale where the salesman's promise actually was honoured, with a good result for a friend of mine.
He lives in the middle of a cabled up and fibred up estate, but his little stretch of road is private, so he has no cabling to his property and no fibre, only ancient drop-wires.  The last quote he was given from NTL was a couple of thousand pounds to lay 20M of cable up to his property.  Hence he has been through several ISPs in the past decade, none of which could get him much beyond 512kbps on ADSL.  A few months ago, a Virgin salesman knocked on his door and cheerfully signed him up to a 50Mbps cable service, unaware that his property was 20 metres away from the nearest section of cable on the estate.
When the engineers came round to connect him up, they found he had no cable. But because the salesman had sealed the deal, they went away and logged a cabling call for him.  I believe it cost him £30 for them to cable to his door, and he is now enjoying 50Mbps broadband for the first ime, and all because a salesman promised him something that the installation teams were forced to deliver.