Straight after the 2010 General Election I had to go on a big adventure. Buy a mobile ‘phone.

I know it sounds simple.

But – like driving a car, riding a ‘bus, or the tube – I hadn’t done this for over thirteen years.

I’d been enveloped in the cocoon they call ‘close protection’, provided by teams of highly skilled police officers. In the months immediately following the election, I still had these officers with me.

Off I went to the store, one detective with me, the other in the car outside. As we left, I heard someone screaming abuse, then thick red liquid on my face, and down my suit.

The detective – also covered in the stuff – bundled me quickly into the car. His job was to keep me safe – and to worry about apprehending our assailant later. (As indeed happened).

The thick liquid turned out to be ketchup – from the next door takeaway. I was shocked, but no more.

Did this encounter mean that my close protection had failed? That, after all, is the allegation that’s been made about the Prime Minister’s close protection ‘allowing’ a jogger to collide with him in Leeds, on Monday.

Absolutely not.

The close protection officers do a near impossible job. They have to keep you safe, whilst allowing you to lead as ‘normal’ a life as possible. Even senior ministers have to be able to meet their constituents, go to the cinema, and football matches.

The ketchup incident wasn’t the only one. There’d been one (with an ‘animal rights’ protester) whilst I was out running, another in a shop, with a sadly crazed woman.

In the United States – where I’ve had protection – they do things differently. Where two officers would be used here, there it may be a dozen. It hasn’t made for any greater safety. Look at the almost-successful assassination attempt on US President Reagan in 1981.

Success for our close protection officers is judged every day by a negative. That no harm comes to their principal. We should be proud of what these brave people do.