That's a lovely picture. Are they field mice?

Thanks Mike-P for helping clear the matter up.

I don't know whether the K-mount is included in the conversion service; the other mounts are much easier to swap as they are all electronic, but the Pentax version needs further internal changes.

I am still of the view that this is one exposure practiced over hundreds or thousands of times to get everything to work as it should, and finally getting the timing spot on. Getting the balance of flood and flash right is the key, and I guess takes care of the variables from natural light. With the flash being brighter than the flood that would overlay any blurring, also if the flood was to one side and the flash was on camera the highly reflective feathers would come out much brighter on the flash. If you have seen a kingfisher you would know what that means, it wouldn't work so well on a sparrow for example.

Why not use a phone film protector cut to size?

Nice point McGregNi, there is a debate going on about whether flash should be used on birds and especially owls due to the effect on their vision, temporary or otherwise. It must be viewed as an unwelcome intrusion into the natural world. This setup must have been in place for months for the bird to get used to the flood and flash, so possibly it was still a successful fishing spot and the lights didn't spoil the kingfisher's vision. Or did the flood actually help see the fish in the dim light? I have seen other examples of flash-lit birds which render very unnatural looking images, and it is not something I would consider.

The explanation is all there on the first link, no speculation needed.

As I recall there were two light sources, one flood which lit the movement which you see as a light blur and the flash which froze the last moment, so all done in camera.

Well SRS should see you right, I appreciate they are a long way from Sunderland so a visit is out of the question!

The flash froze the movement, the 1/15 second exposure allowed the motion blur you see on the bird's descent. You will see the flash was triggered at the end of the exposure to get this effect (trailing curtain) so the effective exposure of the sharp focus part is whatever the flash duration is.