I have an employment contract (in the UK, still just about part of Europe) because I like stability, and building up expertise in one thing rather than chopping

I have an employment contract (in the UK, still just about part of Europe) because I like stability, and building up expertise in one thing rather than chopping and changing every year or two, and because the set of companies doing the kind of work I like doing isn't really that large. Raw salary isn't everything...