If proof were needed that politics is a ruthless business, Amber Rudd’s sudden departure from one of the three great offices of State is surely clear evidence. It is often said that the Home Office is a bed of nails destined to keep even the best political brains awake at night.

Why is this?

The dramatic and unexpected are the hallmark of politics and the Home office portfolio of responsibilities certainly provide plenty of that. Policing, security and immigration policy are always going to be harbingers of trouble. It has always been so.

Yet the Home office today is much reduced from its former size and range of responsibilities. When John Reid was Home Secretary in a previous Blair administration, he memorably said that the Department was “not fit for purpose”. Blair removed prisons and justice to the new Department of Justice and responsibility for broadcasting policy went to what became DCMS.

The Home Office had five ministers back then and even with a reduced but different range of duties today still has five. Whether these changes enhanced the good management of government is open to question.

Today the five ministers have clear responsibilities: immigration, security and economic crime, policing and fire services, countering terrorism, and disclosure and barring services. All these areas have have the potential to blow up in the media for one reason or another and often do.

Can politicians cope with these policy issues?

Good civil servants will provide excellent briefs, but we ask a great deal of elected politicians. The democratic process brings people into the House of Commons from a wide range of backgrounds and few would have had working experience of managing the complex range of issues that modern ministerial service throws at them. None, if any, come trained for ministerial office. Little wonder then that things can and do grow wrong.

What advice would I give as a former minister to new minsters? Firstly, listen and trust the briefings from civil servants. They are independent objective professionals.

But most importantly spend time on visits to services and meet officials to see how things are really working out in practice. It requires an investment in time but it is essential.

Looking at the Windrush debacle, it seems incredible to me that the minister for immigration did not see this problem coming down the track.

Amber Rudd has paid the price for that failure. She is not the first and, alas, she will not be the last to leave office in the full glare of publicity, for that is the nature of politics and always will be as long as we live in a democratic society with a free press and Parliamentary scrutiny.

But the lesson is clear. The Home Office, one of the oldest departments of State having been established in 1782, is complex. It always requires political savvy and attention to detail.

Sir John Wheeler is a former Northern Ireland minister and served as a Member of Parliament from 1979 to 1997.