Mon - Fri VLM's LCY is scheduled into IOM at 0955 and departing at 1610. according to their website. As they operate nothing else out of IOM this means the aircraft is sat around for about 6 hours!
And the crew head to an hotel to for a rest period. Guess
(a) parking at IOM is a whole lot cheaper than LCY (and cheaper at JER as well 'cos there's another aircraft there all day as well)
(b) the crew gets to work a 12+ hour day thanks to the rest