Hi Jimbo,
If you were perhaps 10% over the limit - so 55 mph, you 'might' have been offered the speed awareness course where you pay an amount and go for half a day at a local place to get the presentations and warnings etc about speeding etc. This also means there's no points recorded on your license. Sometimes people will say they were 10% over and +1 or 2mph on top, so 56/57 mph (in your case) and were offered the course and other's weren't offered it.
As you mention, it was on the M4, was it in a roadworks zone by any chance? Unfortunately, I think the course isn't offered if you are caught on the motorway and less chance of it if it was in a roadworks. For the 'variable speed' limit sections of very busy motorway around the UK, it's always best to stay below the limit shown in the red circle and the same for roadwork sections - you'll wonder why other's go zipping by you at 5-10-20 mph quicker than you, but just ignore it and stay within the limit!
I had a speed awareness course perhaps 4 years ago now and it does make you realize about why speed limits are in place, along with how to tell which stretches of road have which limit etc. For me, it did have a good impact on my driving in terms of more awareness.
KFdancer - Agreed, parking costs are high, as a family we hardly ever park at Heathrow, we just call ahead and go to the departures point and pickup the person/family there for instance. Every now and again we do have to park and I had to a few weeks ago and 2 hours was £12 or so which I didn't like, however I know it's quite a bit less than other car park charges! In other places, for years now I've found where the 'free' parking is if I need to visit there semi regularly. I got caught out a month or so ago for driving in a bus lane that was literally 20 yards long and next to it was a width restriction. The vehicle I was in at the time was a van, so might not have squeezed through. The worst part? I did it twice on that day and again a week later one time (a client site visit) so 3 fines at up to £195.. EACH! I sent in a letter, but they decided (correctly) I should have paid more attention to the width restriction warnings further down the road - I missed those! I got an extension to pay the reduced charge of £65 each and so just coughed up that!
Cheers, DtM! West London & Slough UK!