04/06/2013 13:09 BST | Updated 04/08/2013 06:12 BST

To Serve and Protect

By Roger Hurn author of Business is Murder

I was at King's Cross Station last Thursday waiting to catch the 10.45 First Capital Connect train to Cambridge when an announcement came over the tannoy that the train was delayed. Nothing usual about that, I thought, but suddenly a rumour whipped through the crowd of my fellow passengers at the barrier that a bigwig was boarding in the First Class carriage and that's why we were waiting. Naturally, we were all pretty fed up to hear this. Who was it whose business was so important that the rest of us had to wait? Then words spread that the bigwig was none other than Queen Elizabeth.

I think we were all amazed that the Head of State was travelling on public transport the day after the horrific murder of the young soldier Lee Rigby on the streets of Woolwich. It showed courage and a determination on the part of the Queen to carry on and not be intimated by the threats posed by those who think nothing of wantonly taking innocent lives. It also demonstrated to me that she had absolute faith in those charged with protecting her.

There was a uniformed police presence and the Queen had plain clothes Royal Protection officers close at hand. However, although everyone was alert and watchful, we members of the general public were allowed to stroll past Her Majesty's carriage with the minimum of fuss. Lots of people took pictures on their mobile phones of the small woman in a beige outfit and a pink hat who smiled and seemed perfectly relaxed.

'I can't believe that I've just been up close and personal with the Queen,' one excited passenger told me. She wasn't the only one either, but I was more impressed with the quiet efficiency of those officers charged with the difficult job of protecting the Head of State whilst, at the same time, allowing members of the public to go about their business in such close proximity to the Queen.

When we all disembarked at Cambridge, I was only a few steps away from her and I stopped to gawp. Immediately an officer gently but firmly asked me to keep moving along the platform and I appreciated the tactful way in which he made this request. I wasn't surprised however because, in the course of my research into the Diplomatic Protection Group for my novella Business is Murder, I had met several of its officers and realised that they do a difficult and demanding job with patience and courtesy whilst maintaining a high level of vigilance.

'When you're on someone's shoulder,' one DPG man said to me, 'They have got to know that they can trust you to react instantly to deal with any situation. You're as much use as a chocolate teapot if you freeze when it all kicks off. But that's our job, to keep those in our charge safe and to do it professionally and without alienating the general public.'

Last Thursday, on a day when the officers protecting the Queen had every reason to be fearful for her safety and impatient with the general public, I'd say they succeeded admirably.

Roger Hurn is the author of Business is Murder, featuring ex DPG officer Ryan Kyd. The ebook is in Kindle Singles programme.