St Pancras International station is probably the most beautiful rail terminus in the world. From here you can travel to Sheffield, Brighton, Canterbury… or along the UK’s fastest railway, High Speed One to the Channel Tunnel and the Continent.

For over 20 years I’ve been travelling on Eurostar - from London to Paris, Brussels and the south of France - with scarcely a thought for the process of getting there. Such as: who are the men and women who drive the fastest trains in Britain, and how are they trained?

So I asked Eurostar if I could get a glimpse inside the operation — which began in an office building beside King’s Cross station in London. It’s Eurostar’s UK home, and training base for some of the 200 drivers — one-third of whom are British, the remainder French and Belgian.

Before you get a job as a Eurostar driver, you must have at least three years experience with another train operator. The new recruits are then trained for a year, including a course in French.

Just as with planes, trains have simulators — which allow new recruits to master the operational basics and deal with a whole range of possible scenarios. The set up is very realistic, with what you see on the screen responding to your control inputs.

If you’re a Eurostar regular, there’s a good chance that you’ll have travelled aboard the new breed of trains, codename e320. For drivers old and new it’s a very different experience, and the difference is clear from the simulator — I’d characterise it as a great leap forward of about 30 years, from the clunky old 20th century into the brave new 21st. In the implausible event that I were ever offered the chance to drive a real train, count me in for an e320 — and that 320 stands for the top speed, almost 200mph, though they don’t run quite that fast en route to Paris.

After the training, I clocked in to watch the real thing — aboard the 3.13pm non-stop train to Paris, in the company of Pete Walker.

Eurostar trains don’t have the tracks to themselves; they slot into some ferociously complex schedules alongside Southeastern trains, Eurotunnel shuttles, French domestic services and Thalys international trains. So punctuality is second only to safety.

With two minutes remaining before our scheduled departure time, all the passengers were on board and the doors closed. Next stop Paris, so long as the signals are kind.

A green light, the traditional signalling system in the UK, gave us the go-ahead, but within a couple of hundred yards radio-controlled cab signalling began — and lasted all the way to the outskirts of Paris.

We sped through the tunnel beneath east London, came up for air briefly and then dived under the Thames, emerging in Kent a few minutes before the spectacular Medway crossing — on which Eurostar outpaces cars and trucks on the adjacent M2 viaduct by a factor of three to one.

Remarkably, the sensation of speed is muted — even though we were travelling at close to three times the legal limit on the roads. The field of vision is exactly what the driver needs: the line ahead, and any issues that might affect the railway to right or left. Without much input from the sides, which are a blur from the passenger seats, it feels as though time slows down.

Eurostar trains have dedicated paths - time slots - through the Channel Tunnel, though if Eurotunnel shuttles or the freight trains are disrupted, then the trains to Paris and Brussels may be obliged to dawdle.

The next potential area for possible congestion is Lille, though on the day we swept majestically through Lille-Europe station and on to the tight right-hand curve that brings the line from Calais around to join the main Brussels-Paris tracks.

On this stretch, the sheer volume of traffic became apparent with expresses coming the other way every few minutes. Only a few are Eurostar trains — the remainder are bound for Dunkerque, Brussels, Amsterdam and beyond.

The most marvellous moment of the whole trip was about 20 miles short of the French capital. The line climbs a steep gradient, then takes a right-hand bend and there, to the left, is a silhouette of Paris — with the Sacre Coeur in Montmartre and the slender, elegant Eiffel Tower most prominent.

Driver Pete slows the train to a gentle 160km/h (still 100mph) as we joined the “classic” line on the final approach to Paris, with the signallers guiding us through a tagliatelle of tracks to Gare du Nord.