Invader?

I'm by no means an expert on ladybirds, but this guy caught my eye this morning. We have lots of 2-spot ladybirds here, and 7-spot, but I'm not sure I've seen one of these before.

I've done a bit of searching:
- most British species can be ruled out straight away because of the number of spots,
- it doesn't have light bits round the spots and as far as I can see its head isn't white enough to be an eyed ladybird,
- its head is the right colour to be a cream-streaked ladybird, but it doesn't have cream streaks and I think the spots on its head are too large and fused.

So... is this a variation of the dreaded harlequin ladybird? I know there have been a few sightings in Northern Ireland but so far we've avoided a full invasion. Any insect experts out there feel free to inform me! I'd be happy to hear it's just one of our native species :)