Please remember that some ISPs ensure that popular speedtesters give them good results, and that real world will be different.
In the case of your ISP, Skruntie, they are king of the traffic shapers.
Evenings will cause slowdowns for most, due to the amount of contention on the backhauls.
As speeds increased accros the net I understand they all have enforced bandwith rules.
My limit is 15GB between 4 pm and Midnight. I just hit 11.03 GB peak usage yesterday. But my monthly access restarts tomoorw so I will hit the full 15 GB today.
Off peak they leave me alone, for that reason I am 100% with them, that is of course unless they change.
My speed test actually reported a slower speed then I was downloading at when I did the test this morning.
Plusnet are renown for the amount of traffic shaping they do, far worse than any other big ISP. Not knocking them for it, thats their model, and it protects the customer they want to keep (low users), and hurts the ones they want to drop (heavy users). Plusnet's problem has been shown time and time again, they have insufficient Central capacity (these puppies are over £1m per year), hence the extreme shaping.
If it works for you, brilliant

But my point remains, the speedtest means jack schmit

(and ain't that great either)