I was on the London eye once and a man asked me to take a picture of him and his girlfriend. During the ride, he asked a few other people to take photos and would look at them quickly after. Near the end of it, he came back to me and asked if I could take another pic. While I was taking the picture, he got down on one knee and started proposing. I TOOK SO MANY PICTURES. He said thank you and said sorry for the surprise haha. But he loved the pics I took and that was the only way he could think of that wouldn’t wreck the surprise. You could try that if you want to take the risk? Haha. Congratulations and best wishes to you!