Thank you. First of all there is not really a data protection issues necessarily unless you know what actually happened with your file. The employer is not legally obliged to retain your file for any specific period of time after you leave so they could have simply destroyed it and not made it clear to everyone that may have access to it that this was the case. So unless you can show that it has not been stored securely and gone into the wrong hands it would be very difficult to try and argue any breach of data protection, let alone claim for it.
As to the contents of the reference, the only issue would be the comment not to re-employ you. The rest they are allowed to include because they can be economical with the facts if they wanted to and can only provide basic details if that is what they want. In fact they do not even have to provide a reference.
So in relation to the comment, you have to be realistic with a defamation claim as that is certainly not as easy as one may assume. It will cost you upwards of £10,000 to make such claim and you also have to consider that whether the party alleged of making the defamatory statement can defend the claim. Even if you satisfy the criteria to prove the statement was defamatory it could be defended on a number of grounds, including by providing evidence that the statement was substantially true or an honest opinion.
If the referee does provide a reference, then it owes the subject a duty to take reasonable care to ensure the information it contains is true, accurate and fair, and does not give a misleading impression. Referees must therefore be able to justify and support any comments made in a reference and show either that they are true or that they honestly believe that the contents of a reference are true. So instead of defamation you may consider suing for negligence instead, if the comments they made were negligent and not being able to be backed up by any objective evidence.
This is your basic legal position. I have more detailed advice for you in terms of the steps you must take to proceee with this, which I wish to discuss so please take a second to leave a positive rating for the service so far (by selecting 3, 4 or 5 stars) and I can continue with that and answer any further questions you may have. Don’t worry, there is no extra cost and leaving a rating will not close the question and we can continue this discussion. Thank you