Moved house with fibre; now very slow - contention or fault?

[#1]

I had fibre at my old house, in a relatively rural village and was getting a very decent speed from a cabinet ~400m away - very close to the upper bounds of what FTTC can provide (I only had the 40Mbps service, and using Ookla speedtest was always getting > 30Mbps). Simultaneous Netfix/iplayer streams - no problem. I was very happy with my upgrade to fibre from 2.5Mbps ADSL.
Last week I moved to a more urban location near a major city and the speed is ridiculously low - at least when I'm awake.
A BT speedtest result at 10pm this evening came back as 1Mbps down, 1.5Mbps up (IP Profiles say 38.72 down/2 up). There is less than 50m between me and the FTTC cabinet:

Quote

Download speed achieved during the test was - 1.09 Mbps For your connection, the acceptable range of speeds is 20 Mbps-38.72 Mbps . Additional Information: IP Profile for your line is - 38.72 Mbps

I will try another test late tonight / early tomorrow morning - and I expect I will see a much higher result.
Can infrastructure contention be this bad, or is there a fault somewhere?

[#2]

And measured at 6am:
Down: 37.77 Mbps
Up: 1.83 Mbps
Ping: 37.63ms

[#3]

You maybe suffering from being on the wrong gateway.
This issue is discussed in length on the "Capacity Issues" And "Capacity Issues continued" threads.
Check your gateway at http://usertools.plus.net/@gateway/
Myself and others have issues when using gateways end in BNG at peak times only.
Currently I'm on ptw-ag02 and I'm not experiencing any issues.
To change gateways, log onto your router and use the disconnect option. Wait 30 seconds and then connect again. Once back on-line, check the gateway. It should have changed (not guaranteed). Note down what it is and then check you speeds now and again tonight in peak times.
I now keep a log file on when gateways change and the results.
Hope this helps.