Votes gained or lost since 2010 in By Elections

DoktorB has found this interesting set of numbers.

In those constituencies where byelections have been held since 2010, principle party vote changes are:

Conservative down 105,498 or 63.4%
Labour down 87,101 or 31.5%
LibDem down 90,374 or 66.0%

UKIP up 29,718 or, 187.6%
Greens up 399, or 9%

BNP down 16,110 or 66.2%

Respect, btw, are up 19,491 votes almost entirely due to George Galloway, an improvement on 2010 by some 1,285%, if such things have been calculated properly.