I did understand his comment, Trailer forums appear to be few and far between.Being an engineer I have built a few standard trailers in the past, but to be honest this is far cheaper with a more useable result.
Total cost up to date is
Back of car £50
Cutting ( Discs and labour ) £25
Two wheels with tyres £40
Puncture repair £5
Still need Struts for read tail gate.
The hitch and box section are free as I have had them for years, just need to find something to fill the hole in now.
I have had a good look at the legalities and as long as the lighting is correct and the two Triangle reflectors, possibly a maximum weight plate it should be fine.
Some info here
http://www.trailerforum.co.uk/showthread.php?t=93999
Basically I can prove its well engineered and can keep a set of basic calcs for the loadings etc
What I will check on is I am not manufacturing these, its a on off built for our own use, I will ring VOSA and ask the question though as the last thing I need is a problem with it as it will draw attention