Under UK employment law it is ILLEGAL to give a bad reference! One can refuse to give a reference, which in itself may speak volumes, but it is against the law to deliberately give a bad reference. I'm sure I know the disgusting individual you are referring to, and it does not surprise me in the least. I believe you have a strong case to take this higher... Whether you wish to of course, is another matter. In any case, you have my sympathies.