Gulls notoriously dislike confined spaces. They need quite a bit of room to take off and land so will very rarely land in a small, fenced or walled garden.
But they will risk it when they are cold and hungry. Fifteen black-headed gulls and one immature common gull have just finished fighting over some old bread and cake I soaked and threw out on the lawn. Feeding frenzy doesn't begin to describe it.
Nice pair of blackcaps on the bird feeder though.