Yes, Andrew, my enquiry was indeed in respect of the Thinkbroadband speedtest, on my adsl service (which is pretty dire at the moment). But it's the 'variability' of response time that is annoying the hell out of me. I've seen Latency times up in the 300mS range although it isn't all that common.
In terms of distance from London, well 38 miles from Piccadilly doesn't seem that far! [I'm in SW Bedfordshire] Yet it sometimes feels like I've seen Ravens give a faster service (as in Game of Thrones!).