Is this a ground cover plant?

Probably variegated Vinca Major. If it bears purple flowers later, then it's definitely that.
Good ground cover plant but a bit invasive.

I agree with Bertie. Mine flowers around april-may though. I find it useful in difficult shady spots but you do need to watch out for it travelling...

the leaves are quite small so you may be lucky and have the variegated vinca minor, less of a thug. either white or blue/purple flowers.

I don't think the leaves are the right shape for V. minor which tends to be more thin and pointed. I find the variegated minors a bit 'dusty' looking so I'd rather have major, but that's just a matter of individual preference. :)

I have Vinca Major. It is a tough plant, and useful for difficult places. It does help to light up a dull corner, and I grow it where workmen's feet tend to tread because of its robustness. It flowers better in sun and semi shade than in full shade. Grown where too happy it will spread about a lot. But grown where a little less happy, it will still do well, but not behave quite as invasively. I have a collection of Vinca Minors also, which I love. But for its purposes, I actually rate V Major quite highly. I have noticed mine spreading by underground runners often, but haven't observed any surface runners, though I wouldn't be surprised if it were to.

Thank you all for the comprehensive info. We already have Vinca minor and this one has larger leaves. I guessed it would need watching which I don't mind doing and prefer this to a plant that sulks in a corner and won't tell me what's wrong!