YES. If you accept you are making a verbal contract with the school, which is as binding as one you've signed. And yes - heads do tell other heads if someone breaks such a legal contract. You'd have something to say about it if you were offered a post and then the head rang you a while later to tell you s/he's found someone s/he liked better and so the offer is withdrawn - wouldn't you? I need also to tell you that advertising jobs costs a flippin' fortune, together with the time and effort it takes to interview candidates. Schools have increasingly reduced budgets - and money wasted on advertising and interviewing a candidate who then acts unprofessionally is money lost to children and teachers. By the way 'dream' jobs. We get people on here every year telling us they've found their 'dream' job and some of them come back later saying how awful it is.