Hi Andrew..The field stand spring clip mounting plate with the clip mounted to it are the parts that are missing from your list. The clip is mounted on a small plate and the plate fits over the stud. The clip mounting plate is approx. 1/4" thick....Ian
email (option): ian@wright52.plus.com
The clip mounting plate is approx. 1/4" thick....Ian
Actually, 4.2mm
Total length 56mm, width 25.4mm (must be 1"...), one hole 8.2 mm and the other 10 mm. Offset about 5 mm.
email (option): viaconsu # planet dot nl
thanks very much guys. This would make sense, after reading your replies and much searching I have found this photo of what was there before. So now I need to get this part and a side stand? Anyone please?
You are all a great help
email (option): andrew.honychurch@btinternet.com
Hi Hans..The plate only has one bend in it. This turns the field stand clip to the same angle as the stand lies when in the upward position.
In other words it turns the clip so that it is at 90 degrees to the raised stand leg, to ease engagement with the clip and for the clip to grasp the leg correctly once engaged...Ian
email (option): ian@wright52.plus.com
Hey, funny! I always thought mine was original! Came with the bike, but from Egypt, so... 
How much bend do you suggest?
email (option): viaconsu # planet dot nl
Hi Hans..I don't have one off a bike to measure the angle...The key thing is that the clip, when mounted to the plate, lies at 90 degrees to the stand leg (when the stand is in its raised position)
When the stand is clipped into position the stand leg lies at an angle relative to the fore and aft centerline of the bike..it is that angle you are after....hope that makes sense...Ian
email (option): ian@wright52.plus.com
I know what you mean Vincent...I came across an original photo many moons ago showing an M20 with a modification in this area. Frustratingly, I have never been able to find that picture again so I'm unable to provide the 'evidence'.
However, the mod. entailed the shortening of the vertical mudguard stay on that side..which was then bolted to the chainguard mounting bracket.
Many original M20 chainguards have a hole in the chainguard bracket in the appropriate position for this. The result is more space on the stud for the clip bracket.
Questions are, was this done for a short period after the introduction of panniers and the relocation of the clip, was the stud length altered at any point and why aren't there more photos of bikes equipped this way?. Also, there don't seem to be any changes to the part numbers for the rear mudguard stays, though I haven't been through every parts list.
It's an odd one...if it was a 'one off' modification why do the chainguards have the hole in them?...Ian
email (option): ian@wright52.plus.com
Hi Andrew..What about the pannier support tubes that also fit to these studs...do you have those?...Ian
email (option): ian@wright52.plus.com
Here is a general shot of what has been discussed. Chain guard, mud guard stays, pannier support tube and the bracket that the field stand clip attaches which has a banana bend in it, all on that stud. You can even see the hole in the chain guard bracket that Ian mentioned. Ron
email (option): ronpier@talk21.com