Like the M3, the M40 can be thought of as the bit up to junction 8 (mostly east-west), a linking section, and the bit after junction 9 (mostly north-south). Let's start with the bit up to junction 8. Junction 1 is the start of the motorway. Junction 1A is for the famous M25. Going west from here there is a sign ``Beaconsfield 4, Oxford 36, Birmingham 100''. (All square numbers!) Just after this, the street lights stop. The next exit is the A355 to Beaconsfield, Amersham and Slough. That sign is amazingly unreflective - is anyone actually responsible for fixing things like that? Junction 3 is restricted: you can only leave westbound and join eastbound. It's another crossing with the A40, this time to High Wycombe. Junction 4 is the A404, leading to the M4, Wycombe, Marlow and Maidenhead. The road loses a lane here. This is actually very annoying and verges on dangerous. At peak times there is a surfeit of people trying to get on to the A404 (and presumably the M4), which makes things worse. There are also some quite nice white street lights at this junction. Junction 5 is just east of the Oxfordshire/Buckinghamshire border, and is another A40 exit, to Stokenchurch and Wycombe West. After that, there is a steep section cutting through a hill (I had a car die trying to get up that once!). There are signs warning of side winds, but I've never experienced any. Junction 6 is the B4009 for Watlington and Princes Risborough, and then it's up to the twin junctions of 7 and 8. Junction 7 is the A329 to Thame, but it only exists going westwards. Junction 8 is the last intersection with the A40, where the road essentially splits, the two-lane A40 keeping the motorway restrictions at first. This used to be the end of the motorway. It should be remarked that the surface east of junction 8 is very, very bad, to the point of being almost unrivalled on a major British road. It used to be bad most of the way from 5 to 8, but they did fix about half of this. Whose idea is it to build roads on the cheap out of that concrete stuff, anyway?
Mike Astbury provides the following information about the services at Junction 8:
We now come to the linking section. This is really quite amazingly dull, to the point that junctions 8 and 9 have warnings on both sides of the carriageway, almost as if they expect you to have fallen asleep since the last junction. Junction 9 is the A34 to Oxford and Newbury, and the A41 to Bicester and Aylesbury. Use both lanes for Oxford A34... but I usually use one or the other. Junction 10 follows soon and meets the A43 to Northampton and the B430 to Middleton Stoney. It also has the Cherwell Valley service station, and a system of two overworked roundabouts. Junction 11 is notable for its smell! It smells like a brewery if the wind is right - there is a Carlsberg place nearby, I think. Meeting here are the A422 and A361; this is the junction to Banbury. Next comes the Oxfordshire/Warwickshire border, which actually crosses the road more than once, explaining why the sign on the other side of the road is so far away. Junction 12 is the B4451 to Gaydon, with its 30 mph advisory limit on the bend. Between 12 and 13 are the Warwick services, with their lack of bridge over the road. Junction 13 is the A452 to Leamington Spa, and so is Junction 14, but 13 is for leaving northbound and joining southbound, and 14 is for the other possibilities. I hope they weren't just trying to pad the numbers out. Junction 15 is the A429 to Warwick and the A46 to Coventry and Stratford, with a big graded roundabout with traffic lights. Formerly, there were no lights, and chaos in the rush hour. Junction 16 is only half a junction, meeting the A3400, which is morally the A34. This junction leaves southbound and joins northbound. After that, the road melts into the Birmingham motorway system (M42, M5, M6) at junction 3A of the M42.
For information on how the M40 relates to futuristic civilisation and addiction to morphine-like chemicals, I refer you to the excellent Scale by Will Self. This is actually very relevant, if you're interested in roads. He's also written some other stuff about the Westway. (Other road-based literature includes the excellent Riddley Walker by Russel Hoban, but this is A-roads only, I'm afraid.)
A puppet size model of Thunderbird 6 was made along with several radio controlled models and shots of these were integrated with the actual flying scenes of a real Tiger Moth. Joan Hughes, an experienced pilot who had flown in many movies prior to Thunderbird 6 flew the flying sequences. During filming of one sequence on the newly constructed M40, Joan along with Production Manager Norman Foster were arrested after she flew under a bridge. Originally she was to taxi under the bridge but crosswinds meant she had to keep flying just a foot or so above the ground. Gerry pleaded to the police that as Producer he should be charged instead. In the end the jury acquitted them on all charges.
Location shooting for the film landed the production crew in court when a sequence involving daredevil stunt flying by ace bi-plane pilot Joan Hughes contravened the instructions of on official from the Ministry of Transport. The scene called for Alan Tracy's Tiger Moth bi-plane to fly under a motorway bridge between junctions 3 and 5 of the M40 (which had just been completed and was not yet open to traffic) near High Wycombe. The Ministry of Transport official insisted that the bi-plane could only pass under the bridge if the wheels were in contact with the road surface, a stipulation that made the stunt significantly more difficult for Joan. Ultimately, a sudden crosswind prevented her from landing the plane and she was forced to fly under the bridge without touching down, or risk losing control of the plane. The Department of Transport prosecuted the crew but the case was thrown out of court. The team was subsequently refused permission to film any more scenes on the M40, so the special effects crew built an entire section of the motorway in miniature on the effects stage to complete the necessary shots. In the finished film, the miniature work was indistinguishable from the material shot on location.
Also, the M40 (Gerrards Cross by-pass) was the first time that a public highway was built out of concrete, using a special laying machine. Interestingly, ``random spacing of the grooves made it impossible for pure tones to be generated by vehicle tyres, which eliminated the objectionable high-pitched whine that can otherwise be produced''. The grooving machine was the result of several years' research by the Cement and Concrete Association.