Anyone have experience of setting up a babysitting circle?

[ConvexBetty]

There are quite a few families in our church who have young children. We would like to try and make it easier for couples and single parents to be able to attend meetings. I have heard/ read a little about a system where people are in a pool for babysitting and have credits. I can't figure out how this would work with say 20 families.
Anyone know how to set something like this up?
We really want to support parents who are feeling isolated or are restricted due to finances or lack of family help.

I used to be in an NCT babysitting circle. We started with a number (can't remember exactly how many, it was several years ago) of vouchers, each representing one (or a half?) hour's babysitting, and used them to 'pay' each other for sitting.

The pros: very reliable, free babysitters experienced enough to leave a baby with. Occasional evenings watching telly while eating someone else's biscuits, with no ironing guilt.

The cons: some people went out more than others. The people who rarely went out ended up with most of the vouchers, while the busy folk ran out. It works best if people are using it for the odd night out, rather than for very regular commitments, unless two families with regular (but different) nights out can come to an arrangement. Having to put other people's children to bed when when you'd just settled your own.

I am part of a similar circle. One member holds the book . If you need a sit you contact the person with the book and they arrange a sitter and keep a record of the points spent /earned.We earn 4 points an hour and double after midnight. Every few months the book is passed on.
One thing I would say as it may not work for single parents as they find it had to sit and look after their own children.