To clarify, I think the comments about pacey contracts is a tangent which developed as part of the broader discussion, rather than being directly applicable to the OP's situation.
I absolutely agree that you should take proper legal advice, and not rely on replies from an online forum. Even if you have a law degree, you still need the neutral opinion of a disinterested solicitor,as you are 'involved'.
The truth is, you'll get a lot of duff advice based on people's anecdotal experience, rather than a proper legal position based on what's likely if a case goes all the way to court. Some childcare providers genuine believe they are in the right simply because some parents cave in the moment they get a letter from a legal department. OTOH some parents believe they are right because a CM caved in under the threat of malicious attacks on their reputation and character, which could utterly ruin their livelihood.
I would maintain that the CM is responsible for the loss of the shoe. The whole point of the role is that they are responsible for the child, and whatever the child does. You can't have it both ways: you take the money for taking responsibility. That said, the value of the shoes is practically negligible.
Also worth pointing out that the contracted level of late payment charge is excessive, and therefore likely to be ruled inapplicable by a court. Contrary to what many people think, you can't enforce something just because it's in a signed contract. If it's unreasonable, a court will throw it out.
The real underlying problem is that childcare fees are too low to allow for probable costs, including the loss of property, and CMs are doing parents a favour over term-time only arrangements, but at some cost to their own financial sustainability.