Good start to what I know will be problems ahead

[#1]

Better than estimate and over WiFi  

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Phone exchange:RUNCORN EAST Estimated line speed:17Mb (Download speed could vary depending on line conditions. Estimates are the maximum speeds that your phone line can support. These speeds are dependent on the package you choose.) Checked on 2015-09-14 16:52:33 Current line speed:21 Mb

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Download speed achieved during the test was - 20.73 Mbps For your connection, the acceptable range of speeds is  20.84 Mbps-29.77 Mbps . Additional Information: IP Profile for your line is - 29.77 Mbps

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Upload speed achieved during the test was - 4.11Mbps Additional Information: Upstream Rate IP profile on your line is - 10 Mbps

Seems like BTw's profiles are a bit OTT - is this the norm for FTTC?
BTw seems to hope for more of the line ... I waits to see.  

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FTTC Range A (Clean) 25-17.6 / 4.3-2.5 -- Available FTTC Range B (Impacted) 19.6-8.7 / 4-1.2 -- Available

[#2]

Well I hope the Current Line Speed updated to match the 29.77Mbps IP Profile for the line - or did that only last for the first 24hours?

[#3]

Hard to believe that we are nearly 3 months on since the line was connected.  It has all looked fairly stable - however with the combination of the locked down BT modem and the 2704n router which does not support WAN pings its darned near impossible for meddlesome users to obtain useful stats by which to measure the service's performance.
In answer to AO's question (I'd not forgotten it, just been very busy) I checked the figures about a month ago and they were the same as previously reported.  On checking today, the reported 'current speed' has fallen to 21Mbps.
Must do a speed test again next time I am on site.