Meghan Markle is nervous with the Queen according to body language expert

At over 150 years old, the Royal Train is the only private, non-commercial train service catering to one family still in operation in the UK.

The train came into existence during the reign of Queen Victoria who was the first reigning sovereign to make a train journey when she travelled from Slough to Paddington, London, on June 13, 1842.

In 1869 she commissioned a special pair of coaches at a cost of £1,800: a considerable sum in those days. Victoria remains to this day the only monarch to have paid with her own money for Royal carriages to be built.

When her son succeeded to the throne as Edward VII, he ordered a completely new Royal Train in the second year of his reign, 1902, with the instructions that ‘it is to be as much like the Royal Yacht as possible’.

Royal sleepover! The monarch has invited Meghan to accompany her for a day of engagements on Thursday and the pair will travel together on board the Royal Train (pictured)

The interior had bedrooms, dressing rooms, day rooms and a smoking room. It boasted three-speed electric fans, electric radiators and cookers and even an electric cigar lighter.

The King’s favourite was his smoking room, which was manned by two liveried footmen, one just to light His Majesty’s cigars and the other to adjust the curtains and windows in case the sunlight was too strong, or fresh air was required.

His son and successor, George V, had the distinction of installing the first bath on a train anywhere in the world.

While Queen Victoria’s was the first train in the world to have a lavatory installed on board – in 1850, at the suggestion of Prince Albert – only the Prince Consort used it in the early days of Royal progress. 

Members of the entourage who invariably accompanied the Queen had to wait until the train stopped and then use public lavatories.

While the train is fitted with several sleeper carriages the locomotive never travels through the night, instead making stops at secret locations away from the mainline so that the royal passengers can sleep uninterrupted.

The overnight stops are usually made about an hour’s travelling time from the final destination. 

This means the Royals are able to rise, bathe, dress, have a leisurely breakfast and then be briefed by their private secretary on the day’s programme as the train completes its journey. Arrivals are usually timed so that they do not disrupt any normal rail schedules.

The appearance of the Queen’s current saloon is a long way from the velvet interiors and plush furnishings of carriages of the Victorian era.

Today the carriages are fitted with far simpler furnishings with a light wood cladding and each window fitted with a pair of drapes to ensure the utmost privacy.