simonhanmer wrote: This is relatively straightforward if you've got access to the server (luckily I have), but does feel like something that should be included functionality 
Feel free to contribute or sponsor such a feature.
There are loads of great feature ideas that should be included into Limesurvey but unfortunately resources are scarces and not everything can be implemented.
Remember, this is an open source survey tool that you can install for free on your server. And the success of such a tool highly depends on the community and the users giving back to the tool, in form of code contributions, bug solving, translating, helping in the forums, sponsor features/plugins, etc.