LGW
Before we all get two carried away with Jet2 and Gatwick. Stansted covers the London market for them. I don’t see any carrier taking the risk of splitting the market and operating half full flights in the next year or so. There remains the possibility they could up sticks and move to LGW entirely after COVID as, I imagine, the slots would be available and the airport would welcome them with open arms. on the other hand however all the crew are Stansted based, they have a full self handling operation at Stansted and I imagine they have a legal agreement in place with Stansted airport to cover the discounts that they almost certainly have.
In my opinion I think it’s unlikely, but not impossible, they would move south of the river after this.