It’s all done on the London Stock Exchange. As soon as you set up a Stop order this is sent to the LSE trading system and remains “unelected”/“parked” until the stop price is met. Once the last trade price has met your stop price then it is “injected” into the trading system as regular order
Side note: I really wish FT developed Stop Limit orders!
Sometimes the price doesn’t update within the app.
I have mentioned it to the team on the customer service chats and sent screenshots.
If this happens and the price reaches a point where a stop loss order or limit order is due to execute, but something is up with the app on a particular users phone will the trade still execute at the desired price set on the order type, even though the live pricing may be malfunctioning for that user, at that moment in time.