It appears they have been identified, by a friend of mine as 'Red Velvet Mites'

This is the info I found on them:

The small red creatures (appox 1mm in length) are commonly known as red velvet mites, Allothrombium fuliginosum. This animal overwinters as adult mites in the soil and it is most frequently found at this time of year when it is seen crawling over the soil surface, patio and pavement areas. It is not a harmful mite as the early stages feed as external parasites on certain insects, particularly aphids. The older mite nymphs and the adults feed as predators on aphids. Velvet mites are widely distributed in Britain and may have some effect in reducing aphid infestations, although their impact is likely to be much less than that of other aphid predators, such as ladybirds and hoverfly larvae. Harmless to vegetation and animals / humans.

Also.....
Can this really be said of one of nature's hairy eight-legged arthropods? Absolutely, if it's a red velvet mite. Long a favorite of biologists and children, these ruby gems of the family Trombidiidae are most often sighted on the woodland floors of the world, with millions inhabiting the woods of the Chicago Wilderness region.

"Under the microscope they are beautiful!" says Liam Heneghan, an ecosystem ecologist at DePaul University. "They look like a thumbprint." Most red velvet mites are egg-shaped and less than a millimeter in length. Fine decorative hairs, some of which may serve as feelers, give the creatures their lush red velvet appearance.

Though lovely to the eye, red velvet mites are disliked by the palate: their color may warn predators to the mites' unpleasant taste. "There are stories about biologists popping them into their mouths," says George Hammond, a University of Michigan graduate student who studies velvet mites. Other than ill-advised scientists, however, he knows of no natural enemies of these arachnids: "I've put them on an anthill and no ant would touch them."

Heneghan describes red velvet mites as chelicerates. This means that they have tiny lobster-like claws that serve as mouthparts, a feature that relates them closely to spiders, scorpions, and harvestmen.

Sensitive to humidity and apt to dry out easily, red velvet mites make their home in the litter layer of woodlands and forests. They live from one to several years, Hammond says, depending on the species. As larvae, they attach themselves to a variety of arthropods and feed parasitically. They will suck blood from a gnat or grasshopper, for instance, sometimes hitching a ride with several other mites. When red velvet mites become nymphs and then adults, they take to the soil to devour much smaller prey, including other mites and their eggs, the eggs of insects and snails, and primitive wingless insects. Unlike their brethren the chigger and the tick, the velvets keep their mouthparts off of humans.

The presence of red velvet mites is extremely important to the environment. "These mites are part of a community of soil arthropods that is critical in terms of rates of decomposition in woodlands and in maintaining the structure of the entire ecosystem," says Heneghan. "By feeding on insects that eat fungi and bacteria, they stimulate the decomposition process. And when they are removed from the area, many critical processes in the soil go much slower."

Hammond and Heneghan say they've studied the red velvet mite mating dance, and it's not to be missed. The males release their sperm on small twigs or stalks, in areas that Heneghan likes to refer to as "love gardens." Hammond likens them to an array of tiny golf balls on tees.

That ritual is followed by the male laying down an intricate silken trail to the sperm. Females spot these "artistic" trails, then seek out the individual artist. If he's to her liking, she sits in the sperm. But, warns Heneghan, it's a brutal world out there. If another male spots one of these love gardens, he'll promptly trounce it and lay his own.

The planet is home to millions upon millions of mites. Biologists believe there may be thousands of species of red velvet mite alone. Mites remain an under-researched enigma, says Heneghan. "I think we have no real idea what their role is," he continues. "We've only come to realize the importance of the food web in the soil in the last 15 to 20 years. It is the great undiscovered frontier."

Amazing whats in your back garden!