She is waiting till she has a clutch say 6-12 could be more or less. She will then go broody and try to hatch them. If you pick them up each day she will not go broody if you leave them she will.
Last year I got 4 American Blue geese from Holderreads, and I love them. This year if everything works out I hope to get another pair of blues and a pair of dewlap. I think its cool you have a Holderreads goose all the way over in the UK.