example:
http://www.dorothyperkins.com/webapp/wcs/stores/servlet/ProductDisplay?beginIndex=0&viewAllFlag=&catalogId=33053&storeId=12552&productId=4236214&langId=-1&sort_field=Relevance&categoryId=208783&parent_categoryId=226988&pageSize=20
^ hit
http://www.dorothyperkins.com/webapp/wcs/stores/servlet/ProductDisplay?beginIndex=0&viewAllFlag=&catalogId=33053&storeId=12552&productId=4344719&langId=-1&sort_field=Relevance&categoryId=208783&parent_categoryId=226988&pageSize=20
^horrorshow miss