Photofly
I have personal knowledge of a pilot who tried to apply taxi only time towards an ATPL. The time was specifically disallowed TC, even though it did not effect his application. What it did do was trigger an extremely indepth review of every entry in his log book which delayed the issue of the ATPL by 2 months.
While this is a Canadian example, I suspect the same thing would happen with the CAA.
Bottom line is you do not want any suspect time in your logbook when applying for a proffesional license......