Sorry for the late reply. I've had a look and here is todays speeds in Kbit/s. It's down a bit on the previous reading:

Download: 9.999 kbit/s

Looking at the throughput and it does look to be capped at 10 MBPS:

Max. DSLAM throughput kbit/s: 10000
Attainable throughput kbit/s: 48594
Current throughput kbit/s: 9999

Reading the strange use of "throughput" in those figures as in fact being "Sync speed" or "Connection speed" (which are identical to each other), they clearly show that the DLM had capped the line at 10Mbps.

Yes, quite a severe cap, seems extreme for just a few power cuts!