You really don't understand how the system works. Civil servants are given a task by their political masters which they carry out. They then report back on what can be achieved and what can't. At that point the minister in charge can say carry on, or reset how he wants it to go. On a subject like Brexit the cabinet will also have their say. Davis was the minister in charge of this, yet it is well known that he hardly became involved at all. After he went Raab thought he could be the hard man and force through something different, but eventually decided that the deal wasn't so bad, and signed up to it. At the same time he thought he would be making a pitch for PM, and told rather too many porkies exposing him for what he actually is. These are the politicians who chose through either laziness or ulterior motives to say what the civil servants should do, and failed. The civil servants did negotiate a deal based around May's red lines. Without those the deal could have looked quite different. The question has to be asked, where did those red lines come from? Out of her head seemingly because they were not discussed in the referendum.