Identify blue and red bird

We were driving down a country lane near Haverfordwest in South Wales and I saw a bird in the side of the road that I can't identity in our bird book. Have tried using the bird identifier and Google to no avail. It was on the ground right in the side of the road. About the size and shape of a wagtail . Vivid blue (slightly darker than a kingfisher) on the back, dark coloured tail, vivid red underpants. No other colours that I could see. Any ideas?