This is really a complicated subject, made more so by the legislative documents being re-written and the wording subtly changed as a result.
You will stick the number plate on the bonnet at your own risk! So make of my thoughts below what you will, but I am not an expert and this is a summary of my thoughts before I stuck the front number plate on the bonnet of my 1969 MGB (and previously a Mk1 Mini Cooper). I will say though that I didn't risk it in the 1960s and 70s simply because policing the roads was much more proactive!
Have a read of '
http://www.legislation.gov.uk/uksi/2001 ... ule/2/made '.
My interpretation having read the MoT requirements and the document George refers to is:
1. It depends on the age of the car (by first registration date - not build date!). The key dates for most people here are Pre 1/1/1973, 1/1/1973 to 31/8/2001, and 1/1/2001 onwards.
2. I don't believe the wording allows for number plates fixed to the bonnet for cars registered after 1/1/1973 as from this date the positioning (but with some controlled exceptions) and font style were mandatory. Despite this, Jaguar continued to place number plates on the bonnet of E-Types virtually until the end of production, and Alfa Romeo (I am told by an ex Traffic Policeman) have an exemption from placing the front plate centrally. However many people do stick them on the bonnet, and equally many use the incorrect plate styles, fonts and sizes.
3. For Pre 1/1/1973 the wording seems to be much looser (optional is a word frequently used!) as regards positioning and font. Font is described in terms of height, character width and stroke width, rather than style. Spacing (I believe) has appeared in more recent versions of the document. Within this 'looseness' you might interpret that you can stick the plate on the bonnet! My MGB passed its last MOT without comment. Your argument is strengthened (a little) by the wording of Part 3, B, d, of the above document, if your car is not fitted with bumpers as there is no surface big enough to fit the black background to. Also the wording refers to a flat surface NOT a flat, vertical surface. (Not having bumpers of course as another arguement!).
4. Another aspect of the location is the widespread use of ANPR, and whilst it may be good that ANPR might not be able to read the front plate sometimes, it is a real pain to have your car searched every time you go through Dover because the automatic check-in doesn't detect the number plate!