Re: And the other way round
"The small company (Gigaclear) supplying it was recently made to change all it's advertising material to say "up to" as OFCOM can't understand the technology at all "
Isn't it more likely that it's because the line speed you're talking about doesn't equal throughput?
You'll be sharing bandwidth at some point - a guaranteed, uncontended 100Mbps to an Internet peering point is going to set you back at least £800 a month outside of London - so while you may have a 100Mbps local tail, you definitely don't have it all the way to the edge of the Internet. Your backhaul is shared, 100Mbps isn't guaranteed and so it can't be advertised as such.