Even in Scotland that is not the case anymore - it's misunderstod that once you have shaken hands on the deal then that's it done and dusted. Technically until missives are exchanged then you are not tied into the deal - in the past, missives would be exchanged fairly quickly and it was a formality. Nowadays, people hold off signing the missives as long as they can get away with and quite often pull out before they do so and leave sellers (and sometimes buyers) adrift. Not nice ;o(.
Unfortunately that's just life and the pain of buying and selling property. The last time we sold we were twice almost at missive signing stage when it went awry. The first time our buyer continued to look for other properties and bought another instead - he didn't even have the curtesy to let us know, we found out through a third party and contacted his lawyers. The second time, the couple genuinly wanted to buy, but wouldn't sign the missives because they didn't have a buyer for their house and didn't want to be tied in. We forced their hand as we couldn't wait in limbo - we were already tied into our purchase, so they pulled out and we had to get a third buyer - we insisted that they sign quickly or we would pull out of the deal.