The highlight of my summer holidays in the Highlands as a child was the sleeper train north.
Clambering aboard in the urban environment of a city like London or York, then drifting off to sleep somewhere indeterminate up the line, the magic was waking up as the train chugged its way through the Cairngorms towards Inverness.
My most vivid memory is of pulling up the window blind to see the sun on the wooden deer fences which lined the track, with the heather-covered hills behind.
The sleeper is completely different from any other train - and all the more exciting for kids - with its long corridors of cabin doors, which open into berths of single or bunk beds, complete with hand basin.
In a handy feature for families travelling together, an interconnecting door between cabins can be unlocked, effectively turning two into one.
My children’s excitement at their first experience of the current Caledonian Sleeper, as guests of operator Serco, mirrored my own more than 40 years ago.
But, remarkably, we may have travelled this month in very similar carriages to those of my own childhood, which have now reached what’s expected to be their final year of operation.
Serco has updated some features, such as introducing new duvets, and other aspects have evolved over the decades, such as the glass water bottles being replaced by plastic.
However, from reading Old Possum’s Book of Practical Cats to the kids as they settled into their bunks, things haven’t changed that much since TS Eliot’s descriptions of the sleeper in Skimbleshanks: The Railway Cat in 1939, such as: “There is every sort of light - you can make it dark or bright; There’s a button that you turn to make a breeze.”
That era is about to end, with brand new sleeper trains due to roll in from Spain next spring.
It could be a defining moment for adults who have lost their childhood enthusiasm for night trains because of the ancient carriages’ idiosyncratic squeaks, rattles and bumps impeding sleep.
If the new coaches - being made by Edinburgh trams builder CAF - provide a smoother ride, that could persuade more parents to try the experience.
Serco has yet to reveal how they might try to entice more families aboard - it currently provides free food for under-12s and access to first class station lounge facilities such as showers.
But some of the new trains’ features may prove tempting, such as double beds, and ensuite showers and toilets.
There are no showers in the current trains, and shared toilets at the end of each coach.
The new fleet will also feature intercoms so passengers can order food and drink without leaving their cabins, like hotel room service - handy for those with little ones getting to sleep.
All these innovations will come at a price, however, and it is yet to be seen how they will be reflected in fare levels.
However, one key aspect that made the sleeper the ideal choice for my Highland holidays of old is no longer available - the ability to take the family car with you.
Motorail - with cars on wagons behind the sleeper carriages - is alas long gone, and Serco has said it is focusing on getting the “Journey of a Night Time” experience right for passengers.
But it must be a case of never say never - who wouldn’t want to skip the 550-mile drive between London and Inverness?