Peter,
I guess I'm the man with experience with both cameras, police and courts.
Right now I only have two SP30s to my name but the overall tally is much higher (and all since 2003).
I really think it's best to accept it; it'll cost you £60 + 3 points (that's what I got for 43mph in a 30mph a few years back). It stays on the licence for 4 years but is only relevant for 3 years.
Regarding insurance, some want to know and some only consider it when insurance comes up for renewal. Best to play safe and let them know. So far most just make a note of it, but one charged me £17 for the points to be added. It's also worth arguing the case with the insurance company as the agents have some lee-way on the quoted amount. I did and it worked.
The thing is we can all be rightly aggrieved by the random allocation of cameras and idiotic speed limits; sadly no amount of ranting is going to change anything. Like you, one of mine was for a 40mph on dual carriageway with 30mph limit. I agree it's quite unbelievable that it's done, but some young up-and-coming local council bod thought it a good idea - probably got zits, a chip on his shoulder and a 1995 Corsa.
I feel very sorry for you and just hope you only get the minimum which you should if you just bung the old acceptance in the post ASAP.
Incidentally, anyone else old enough to remember driving when it was still fun?
No drink-driving rules, no worry about speed limits, no removing cars as MOT failures because of minor defects.
Could argue that the roads are safer now, of course. Its' true as well ....... but just not any fun.
It's that need to check the rear-view mirror and the worry that the BMW behind is an 'unmarked' that removes the all-out pleasure.
Ah ....ROSE-COLOURED SECTACLES?
If I could have my current Maserati back in 1969 I would be the happiest man in the country!