Could it be a Clover mite, Bryobia praetiosa

Way too big for clover mite - they're less than 1mm long. Not very clear pic - could be some sort of tick - any chance you counted how many legs it had?

It's a Red Velvet Mite, Eutrombidium species. It's not an insect, it's an arachnid.

Don't kill it - they wander through the soil and leaf litter eating pest species.

Well I've never seen one of these before in all my years of gardening - it does appear to be a Red Velvet mite (5mm long). but they don't eat pest species, they're parasitic - they suck the blood of any passing spider or insect they come across, without actually killing or injuring them, according to Wildlife Safari. The RHS tells a slightly different story though - they say this creature predates on anything smaller than itself, and that its the larvae that suck blood.

I did come across Velvet Mite on the internet but the pics didn't look too similar to mine but I think that is what it actually is. Very unusual critter I have to say. BTW, it does have 8 legs. Thanks for all of your responses, now I know for sure, I'll look more into it. x

Never come across one either but then there's millions of bugs out there! I checked on naturespot http://www.naturespot.org.uk/species/velvet-mite-0 which has it listed as "UK Status: Common throughout Britain though not well recorded"