Confidence: It might be this.
Notes: From RHS website: http://www.joyofplants.com/wildlife/search.php?o=128
Geophilus carpophagus - a centipede
"This is a slender and very pale brown centipede, two to six centimetres long, that lives in the soil or in leaf matter. Although centipedes are reputed to have 100 legs, these, the longest and leggiest of centipedes, have only around half that number.
These animals are most often seen when there is digging or any other kind of soil disturbance, when the centipede often repeatedly knots and un-knots its body. Although blind, these centipedes sometimes emit a greenish light which is only rarely seen by people because of where the animals live. It is very common in the soil of most gardens."