I can't speak for other engineers, but there's one main reason I would never go into politics. The issues are too big for my comfort level. The scope of the problems politicians try to solve are much, much larger and have far more unknowns than the problems I solve as an engineer. As an engineer I always have to deal with compromises and unknowns, but I can usually get the information I need to get a feel for what those unknowns are and make an informed decision. Decisions politicians make have so many far reaching consequences there's simply no way to get a handle on the unknowns. Even the "known" consequences often hotly debated with no clear answer. Politicians either have to delude themselves into believing they fully understand the tradeoffs or they must admit they are making an uninformed decision. Thanks, but I'll pass.
Regarding Margaret Thatcher, I was watching a television show about the British SAS and the hostage rescue training they do in their kill house. Sometimes political dignitaries would come observe training exercises. Apparently Thatcher insisted on playing the role of the hostage during one exercise (note they train with live ammo) and sat in a chair with several targets around her. The SAS broke into the room and amidst a barrage gunfire and noise eliminated all the targets. When the few seconds of chaos were over, Thatcher was still sitting in her chair looking very dignified while her aide cowered on the floor. She looked at him and said, "Get off the floor <name>, you're embarrassing me."
Iron Lady indeed.