I’d heard that the Embraer 145 performance on a wet runway at SOU was wholly unworkable, prompting a diversion on a soggy day. A payload restriction every day combined with the chance of a diversion or cancellation on a wet day would - I think - be enough to put any airline off.
And bmi couldn’t have been that short of aircraft if they had stopped SOU-MUC and announced LBA-MUC before they ceased to exist ?