The last time I set foot in a medical tent I was worried whether I was about to die.

There was a straightforward answer to my melodramatic question – no, I wasn’t.

But that was thanks in no small part to a team of medical professionals and volunteers all working for St John Ambulance.

I still don’t remember much about collapsing in the 2013 London Marathon before the 18-mile mark due to dehydration, but what has stayed with me is the wonderful care I received.

Since that day I have been on a first aid course with St John Ambulance at its county headquarters in Stevenage and committed to running the same event this April to raise funds for the charity.

And at the weekend I found myself back where I was almost two years earlier, although this time I wasn’t a patient.

An early start yesterday morning meant I arrived just as St John members were setting up their base for the annual Watford Half Marathon.

It’s one of the larger events on the Hertfordshire race calendar, but with fewer than 2,000 runners crossing the line there’s really no comparison with one of the world’s biggest races which draws more than 35,000 athletes to the capital each year.

But the same methodical approach is taken when it comes to keeping everyone safe, and I was invited along to see the first aid team in action.

Leading the event was unit manager Colin West, who has been involved with St John for more than 35 years.

After briefing a 30-strong team, which included both fully qualified paramedics and teenage cadets, some members went out to different posts on the course while others remained at the base by the finish line, where there were two areas to treat more serious incidents and three tents for minor ailments.

Peter Coulson and Chris Love made up the cycle response unit, following the runners along the route in case an instant response was required.

Thankfully the race passed without incident, with six people treated for minor injuries, and most of our time was spent trying to keep warm.

But Colin knows better than anyone the important role they have to play, having resuscitated a football referee during 2007 after he collapsed in the middle of the centre circle while covering an under-18 final in Watford.

He said: “There’s a major amount of planning involved and if we’re not in attendance the event can’t go ahead.

“It’s all about trying to make sure everyone gets round safely but if something does happen we can get to them quickly.”

GP Nigel Ineson – who has been involved with the first aid charity for 20 years and was the designated doctor for Sunday’s event – agrees.

He said: “Of course we hope we’re not required but we’re here if someone is seriously ill and have the equipment and know-how to deal with it.

“It’s fantastic to see 30 people giving up their weekends to help – and this happens all of the time.”

For one St John volunteer the boot – or should I say running shoe – was on the other foot, as Hortencia McKechnie took part in the race, crossing the line in a personal best time of 2hrs 6mins.

The 27-year-old, who is also in training for the London Marathon, has been involved with the charity since her time at university.

She said: “My mum fell down the stairs after collapsing while I was away at uni but if I’d been there I wouldn’t have known what to do.

“So I joined a group and have been involved ever since.

“You feel like you’re doing something useful.”

I had the same desire to learn life-saving skills after my own scary experience, but the question remains why we must wait for something to happen before we take action.

But whether you have first aid skills or not, I know that come April 26 there will be more than 1,000 volunteers on hand to help all the way along the 26.2-mile route.

Once again there will be medical tents like the one I was treated in set up across the capital and, as reassuring as that is, I just hope I won’t be needing them this time around.