Tiny planid larvae? on a solitary bee.
At first thought it might have been a triungulin, but if so its very small.
No identification made yet.
No interactions present.
After an id to genera of the carrier as panurgus by Matt Smith, I estimate the size of the host to be in excess of 10mm, making the hitcher very roughly in the order of 1mm - so it *is* possibly a triungulin, shame I didn't get a clearer picture to count or discount a meloe.
Lat/Lng: 50.2042, -3.7194
OS grid ref: SX773352