In 3 hours and 12 minutes - including 2 stops at marshall's points for food, drink and more suncream - I have completed the 75 km (50 miles). The route was very well organised with a sign at every turn and confirmatory signs just after a lot of them. There were probably some 30+ marshalls both at check points and also major junctions waving riders across if the road was clear.
It seems that I was able to maintain my usual ~16.5 mph that I do on my 11 and 19 mile standard runs, despite the heat and longer course.
You can see the route at http://maps.google.co.uk/maps/ms?client=firefox-a&hl=en&ie=UTF8&msa=0&msid=108414744479040183848.000487febb81a1bde4948&ll=52.235369,0.96302&spn=0.112487,0.267448&z=12
I need to follow up some sponsorship contributions and anticipate the total going over the (revised upwards) £1,250 target. Many thanks to all my sponsors.
Some photos on my JustGiving site http://www.justgiving.com/RTA-Tour-de-Suffolk