Plates fitted on or after 1st September 2001 need not be exclusively BS AU 145d - they can also conform to any other relevant standard or specification recognised for use in an EEA State and which, when in use, offers a performance equivalent to that offered by a plate complying with the British Standard specification. In either case the plate must be marked as to allow identification of that standard or specification.
http://www.statutelaw.gov.uk/legResults.aspx?a ctiveTextDocId=2579139
VOSA incorporated extended checks for compliance with the 2001 regs into the MOT test schedule from 1st October 2007 but a legal hitch meant that these were temporarily suspended as a reason for MOT failure in November. My guess for the suspension (in part) is that the MOT Inspection Manual also specified the BS AU 145d marking requirement without allowing for another equivalent mark.
You can view the MOT Special Notice about suspension of the checks here...
http://www.vosa.gov.uk/vosacorp/repository/Spe cial%20Notice%2010-07.pdf
Regardless of the MOT testing status, non conformity to the 2001 regs is an offence.