I forgot to add that i know of companies house as thats what i used to find out the firm changed its name so i wondered if i could find out the reason for the name change
A registered business may change its name provided it follows the conditions of and completes the relevant CH form (NM01 thru' NM05 or LLNM01 - i.e. a notice of change of name), none of which requires a documented reason for the name change, therefore it is unlikely that CH could supply a reason.