The track record at Mildenhall is actually 49.81. This was set by Kenneth Bjerre on Oct 31st 2007 in heat 5 of a four team tournament which included a Panthers' quartet of Niels-Kristian Iversen, Bjerre, Danny King and Claus Vissing.
The track record was equalled in heat 1 (50.19 Iversen), lowered in heat 2 (50.17 Bjerre), lowered again in heat 4 (50.04 King) before finally being set in heat 5.