As an Imperial's PhD and having spent couple of years doing research there, I can say that big salary is not essentially the main factor. Certainly it is a fact

As an Imperial's PhD and having spent couple of years doing research there, I can say that big salary is not essentially the main factor. Certainly it is a factor, but probably not as big as Pantic thought. The most important factor is the environment. All researchers love an environment which encourages idea exchange. But the university (& the department) doesn't seem to see the point. The environment is not comfortable to work in to begin with, not to be mention about productivity and exchange, though, to be fair, it is a common problems across all academic institutions. So, if you want to keep them, give them a good environment please.