Is the rescuing of stray rabbits allowed?

Yes. They are not protected by the law as they are not classified as wildlife, so it is not illegal.
If they are on the pavement, where they should not be, we can rescue them because they are seen as strays
It is normally residents who call us out to come and help, because they are concerned for the welfare.
If you are concerned about rabbits wondering your neighbourhood, adopt them, have them sterilised, and keep them safe inside your property.
If your grandchildren enjoy seeing them around, adopt them, have them sterilised, and keep them safe inside your property. You will be the coolest grandma/pa ever.