Rather than a bonus consider bumping her hourly rate if your wife and/or you get a pay rise? We did this with a child minder a few years ago and it felt really

Rather than a bonus consider bumping her hourly rate if your wife and/or you get a pay rise? We did this with a child minder a few years ago and it felt really right to share our positive financial situation with the person who was playing such an important role in our family. Although I note you're in the UK so a pay rise might not be on the cards.