Eternally grateful to hairybarsteward's recent recommendation, and not to mention XraySpex for sharing his Bband knowledge and his longstanding support & advice ................. we now have, after said "free" BT Engineer's visit, a new BT socket with built in filter

........... and yet another Router arrived today while Mr BT was here - it's an Orange Livebox, so with all fixes in place the first speeds recorded (with the BT Engineer looking over my shoulder) were: 2.9 Meg D/load & 0.7 Upload. Mr BT said "that's better than you had, but I don't see it going above 6 Meg download" A couple of hours later it's now ..........
" Test1 comprises of two tests
1. Best Effort Test: -provides background information.
Download Speed
12829 Kbps
Max Achievable Speed
21000 Kbps
Download speed achieved during the test was - 12829 Kbps
For your connection, the acceptable range of speeds is 4000-21000 Kbps.
Additional Information:
Your DSL Connection Rate :16064 Kbps(DOWN-STREAM), 1088 Kbps(UP-STREAM)
IP Profile for your line is - 14000 Kbps
2. Upstream Test: -provides background information.
Upload Speed 879 Kbps
Max Achievable Speed 1088 Kbps
>Upload speed achieved during the test was - 879 Kbps
Additional Information:
Upstream Rate IP profile on your line is - 1088 Kbps
We were unable to identify any performance problem with your service at this time.
It is possible that any problem you are currently, or had previously experienced may have been caused by traffic congestion on the Internet or by the server you were accessing responding slowly.
If you continue to encounter a problem with a specific server, please contact the administrator of that server in the first instance."
And to avoid a reprimand off Xray, here are the router stats:
ModulationType ADSL_2plus; LinkType PPPoA; DataPath Fast
Upstream Attenuation 120 Downstream Attenuation 240
Upstream NoiseMargin 56 Downstream NoiseMargin 61
Upstream MaxRate 4293747263 Downstream MaxRate 16064
Upstream CurrRate 1088 Downstream CurrRate 16064
Upstream Power 125 Downstream Power 233
UpTime 21465
So Mr BT would have been ecstatic, if he'd hung around
Only blot on the landscape, is I can't get my wifi computer upstairs to connect to this router, but a phone call after dinner to Orange Customer Support should put that right