MPs shouldn't work for lobbying companies, simple

There are some things that you shouldn't need to say, but unfortunately you have to. Here's one of them:
MPs should not work for lobbying companies.
It's blindingly obvious, and it really is that simple. But as was revealed recently, a few MPs do just that. And even worse, some of them are former Ministers. 
Now let me be clear. All of these MPs are acting within the law. And all of the companies they work for are acting within the law too. But just because something is legal, doesn't mean