Barclays were probably long on the stock on the financial instruments I would have thought as their target price was £14- and they needed a stop loss for that.
You will see that the short only increased by 0.01 but it was done deliberately so that it comes under the radar (anything over 0.5 being shown). I presume this tactic's sole purpose is to put further pressure on the price although in itself the increase is negligible.