UK AIP ENR 3.6
Para 1.1
'Except where otherwise instructed by ATC, holding en route shall be carried out on tracks parallel to the Centre-line of the Airway, turning right at the Reporting Point.'
Para 1.3, para 2.1, and paras 3.1 & 3.2 give exceptions to this rule, however BCN is not one of them and thus is a 'standard' hold as detailed in Para 1.1