The M25 is either one of the greatest transport achievements of the 20th century or one of Britain's largest planning failures, depending on which way you look at it. This booklet takes the former view, celebrating the completion of the circuit in 1986.
It is a self-congratulation exercise for the Department of Transport, running to 60 pages, but it's also a mutual appreciation exercise for all the companies involved, who all have large adverts celebrating what they did and how generally wonderful they are. It's as interesting from a cultural angle as anything else - £899 for a BT carphone?!
Of particular note is the way it quickly skims over the London Ringways plan - a story which, told in full, reveals the M25 as something of a botched sticking-plaster, and not the wondrous thing the booklet seems to claim.
Further reading on some other orbital ideas for London.