Should my PhD thesis be submitted under my legal name? I married during my PhD and changed my legal surname however (for many reasons) I will continue to publish under my maiden name. My (UK) university says that a thesis has to be submitted under the name held in registration records. They seem happy for me to revert my registration to my maiden name so I can submit my thesis as "maiden name" and this means my degree certificate will also have "maiden name".
I think it would make more sense to have the name on the thesis the same as on the published papers that it contains (i.e. maiden name) but would there be any issues with graduating with an old name? I do have birth &amp; marriage certificates that show my maiden name.

Note: As others mentioned in the comments, technically the concept of a "legal name" does not exist in the UK. However, in practice employers, banks, airports etc. ask for evidence of your name and to change a name on a passport, for example, requires a marriage/divorce certificate or deed poll.
You need to pick a name that you'll use in your professional life. Changing that name has a cost. At this early stage, the cost is low. So, if you want to use your married name professionally, then change to it now. Otherwise, use your maiden name for the duration of your career. (This isn't to say you can't switch later, just that the cost increases over time.)


  would there be any issues with graduating with an old name? 


It may create a slight administrative burden, in that you may have to prove that your degree certificate is yours (given that it won't match your legal name).