Having read the Horse and Hound forum on this subject - at length - they believe a lot of it is scaremongering and chinese whispers, although there are people actually sleeping at their yards last night

.
Yes, there are two vehicles involved, a red Land Cruiser and a White Transit van, yes a couple of horses have gone missing, but nothing on the scale they initially purported.
More details will be available in the H and H tomorrow,
Yorkshire, Derby and one in Kent have been mentioned, but not verified.
If you are worried, contact your local Horsewatch or Police - they will tell you if there is a risk in your area.
Just be vigilant, makes you worry though doesn't it?