But for regular passengers, it was the worst possible start to their week – the allure of the brand new Caledonian Sleeper train soon losing its lustre after it arrived in London three-and-a-half hours late.

Company chiefs are likely to brush off the first-day setback as yet another random rail disruption outwith their control – in this case major signalling problems between Glasgow and Edinburgh.

Inaugural Caledonian Sleeper service delayed

However, the train’s locomotive also had to be replaced in the early hours in Edinburgh after developing a suspected fault, which contributed to the late running.

And although the £150 million new fleet is likely to transform overnight rail travel for many, some teething troubles alas conspired to make my trip between Glasgow and London rather less than the amazing experience I had hoped for.

I’ve never slept well on the Sleeper of old – too hot and stuffy, too noisy, and I’ve even found the night lights on the bright side.

But the new carriages sounded promising.

I’d been previously told by those masterminding the upgrade the air conditioning would be “fantastic”, the ride “silky smooth” and the trains as whole tested “within an inch of their lives”.

My cabin or “Club Room” – indicating as having an ensuite toilet/shower wet room – had a comfortably firm mattress, versatile lighting, including handy vertical strips either side of the basin, and charging sockets at either end of the bed.

It felt no larger than its predecessor – the bed even seemed slightly narrower – but there appeared to be more storage space for luggage underneath. But with the upper bunk down and two people sharing, I suspect space will feel just as tight as before.

Maybe I was just unlucky, but the air conditioning didn’t cool the cabin until late into the night, despite being turned to its lowest. Hopefully that was just a glitch. More seriously, an apparently faulty window seal meant it felt like travelling with a car window open.

Black dust particles on the sill by morning seemed to confirm it – and the steward agreed something wasn’t right.

Was it smoother? Perhaps, but I’m afraid with the noise and heat I didn’t notice.

Having a toilet in the cabin was far more pleasant than gingerly venturing down the corridor in your pyjamas.

I had thought of trying the shower before I went to bed, but worried it might wake up neighbouring passengers. I’m not sure I would have had any better luck, though, because when I tried it in the morning, a dribble of water came out and that was it.

Just as well, perhaps, in case I had tried to emulate the veteran rail blogger, The Man in Seat 61, who had posted ‘head and shoulders’ footage of himself having a shower on the new northbound Sleeper hours earlier.

On the upside, the free toiletries from Arran Aromatics are so good I would happily pay for them.

As for the delay, screens at the ends of each carriage alerted passengers to the problems pretty much as soon as they occurred.

Breakfast made up for the lack of sleep, with coffee served in a wee pot with a china cup by cheery staff every bit as friendly and helpful as I remember them, and for which the service is rightly renowned.

New Caledonian Sleeper review: Delays not the only issue with new service