TalkTalk evening performance

Since the year dot my line performance has been pretty much the same whatever the time, but for the last few days there has been a marked drop in evening to the point it is almost unusable, The router seems to be synced at same speed, so my thinking is there may be some network issues, anyone having the same?
FTTC normally 4mb, not great but long line, here's a speed test I eventually managed to run.
http://www.thinkbroadband.com/speedtest/results.html...