I gave your home phone number a quick call, I'm sorry I didn't get speaking to you today. How did things go with the engineer?
I've run a few checks following the visit and the connection looks stable. There is has also been a increase in speed, your sync speed is sitting at 16000 Kbps. How are things with your connection at your end, have you noticed an improvement?
Sorry we were out, @PaddyB. We were probably walking the dog before the rain comes.
Andrew was the engineer who came out at the appointed time. He was charming, efficient and happy to discuss technical issues. He checked the line and confirmed there were no faults but the download speed was about 11Mbps. He shared your view that the problem probably came down to interference and was more likely to be away from the cabinet. He changed the master socket to one of the newer type which, apparently, screens out interference much better than the old type; he also said that it might help to give a better speed. He reset the broadband connection too. At that time, he was registering a download speed of 17 Mbps but did say that it may fall back a little but should maintain between 12 and 14. He said that if the speed dropped below 11, or the instability returned we should get in contact again.
Another tip he gave was that if problems returned, we could listen on 612 Medium Wave and would be able to hear any radio interference.
At present, everything looks good. Measured on the BTWholesale speed tester, I am getting over 15 Mbps Download, about 3 Mbps Upload and the 'Ping' is way down from previous readings, at about 20.
Thank you for all your help and a special word of appreciation for Andrew.