Euro,
Your figures are identical to the classes of vehicles and speeds I've already quoted !
I deliberately left out roads designated as "restricted" as they are usually well signed at 30 mph or have other identifiers such as systems of streetlighting at given distances etc., and the speeds apply equally to all vehicles.
Just to complicate the matter further, roads in 'built up areas' can be locally deemed as 20 mph or 40 mph and above, depending on how built up an area is, or how heavy traffic flow is.
Your assumption that an A Road has to be single carriageway only, is simply not correct and at the risk of boring the pants off anyone still interested enough to be reading, I will quote (not from memory I hasten to add) the legal Act that defines National Speed Limit in the UK.
[[[ Section 88 Road Traffic Regulation Act 1988.
Our National Speed Limits are actually temporary speed limits which must be renewed every 18 months, this is achieved automatically by statutory instrument 1548/78.
The limits are specified under 'The 70 mph, 60 mph and 50 mph (Temporary Speed Limit) Order 1977' and are :-
Dual Carriageway roads 70 mph (except specified sections limited to 50 or 60 mph)
Single Carriageway roads 60 mph (except specified sections limited to 50 mph)
Those sections specified as having lower limits are listed in the schedules of the 1977 Order. ]]]
I warned you it was boring and I can list you loads of A roads in just my local area that are single carriageway.
Michael E,
Without knowing the full circumstances I can only guess that your delivery guy was driving a larger van, which if not car derived and had a maximum laden weight exceeding 2 tonnes (which covers most Transit and similar sizes conveying goods) and he was on a single carriageway, he would be restricted to 50 mph maximum.
I hope this helps,
Ken.