By June Kelly BBC News royal correspondent

William passed officer aptitude tests to gain entry to Sandhurst

Imagine. It is a cold January day, you've arrived in a strange place and you are about to face weeks of physical hardship and people shouting at you.

This will be the scene in the New Year when the latest batch of cadets pitch up at Sandhurst Military Academy.

But the group anxiety may be tempered by the knowledge that sharing the suffering will be the second in line to the throne.

Prince William will become the most senior Royal in recent times to join the Army.

Traditionally the Royals have gone for the Navy. William has spoken of how he wants to be different.

Sandhurst gives the Royals a degree of privacy which they would not get in any other profession

Sandhurst will be home to the second and third in line. Prince Harry is midway through his training.

He has said he's looking forward to the fact that as a new recruit his older brother will have to salute him when he arrives.

It is because Harry got there six months ahead that we have an outsider's limited view of what is awaiting William.

Tough regime

He will have to take his own ironing board (all that kit that needs pressing) and in the first few weeks there will be no alcohol, snatched sleep and green overalls - which Harry has said make you feel like a prison inmate.

When Harry arrived the top brass insisted - as no doubt they will with William - that Royal princes get no special treatment and they have to learn to fit in and be part of a team.

Capturing the future King will be even more lucrative, so with William the hunt will be more intense

Sandhurst gives the Royals a degree of privacy which they would not get in any other profession. It is a closed world. Well almost.

There have been press stories detailing such developments, such as Harry's blistered feet from those painful army boots, all supposedly coming from "insiders".

The paparazzi have been tracking Harry and lying low in the countryside when he's on exercise with his platoon.

Prince William had to perform aptitude tests

Capturing the future King will be even more lucrative, so with William the hunt will be more intense.

But in some ways the Sandhurst phase is easy.

The tough decisions come when William finishes his training and is ready to be let loose on the battlefield.

In an interview last year he said that when he joined up he didn't want to be mollycoddled or wrapped up in cotton wool.

Now 23 he is slowly moving into a new phase in a life which will be all about duty and tradition

He said: "I'd want to go where my men went and I'd want to do what they did." This could be problematic for defence chiefs.

One former senior Army officer, Major General Patrick Cordingley, said he hoped the prince would be sent to "operational zones".

New phase

Could that include somewhere like Iraq? His uncle, Prince Andrew, was a Navy pilot during the Falklands War, when he was second in line to the throne.

Prince William was born the month the war ended, in June 1982.

Now 23, he is slowly moving into a new phase in a life which will be all about duty and tradition.

With his student days over, he's already undertaken his first official trip abroad, become patron of a charity for the homeless, and is about to become President of the Football Association - all steps on the Royal path.