pete those figures doing the rounds are based on models of situations that could arises, we might lose ex amount of billions if a b c and z all managed to line up nothing but a punt , its all part of the game to eventually get the vote overturned or as good as in real terms.
To be fair, they were asked to, and subsequently produced, a number of scenarios based upon a range of possible outcomes - https://www.bankofengland.co.uk/rep...cenarios-and-monetary-and-financial-stability
The media may have focused on one particular of those scenarios, but that doesn't mean others weren't produced.