Prime Minister David Cameron is in Dartmouth today for a naval college visit which is being kept a closely guarded secret.

Mr Cameron is taking the salute at one of the passing out parades which go ahead six times a year at the Britannia Royal Naval College.

But this week the college was refusing to comment in any way about the prime minister's visit.

The Number 10 Downing Street press office was prepared to confirm was that the visit was taking place but would say little else.

A total of 68 young officers will be passing out during the ceremony on the college's parade ground watched by scores of family members and friends.

The ceremony will also include a march past headed by the Royal Marines Band.

Traditionally the college passing out parades – which is the culmination of 30 weeks training for the young officers – take place on a Thursday.

No one at the college was prepared to comment on whether this week's Friday parade had been changed to fit in with the Prime Minister's itinerary.

But a spokesman said: 'It is just he way it has fallen this time.'

The Prime Minister is expected to be helicoptered in and out of the world famous Royal Navy training establishment for officers at Dartmouth.

The Downing Street press spokesman said that information about the visit was being limited because of security reasons.

But he said that the visit would be 'fairly lengthy' from mid morning today onwards.

The information blackout indicates tougher security restrictions than are usually imposed for even top royal visits to the BRNC for the Lord High Admirals Divisions passing out parades which generally take place at the college in the spring.

Over the years the Queen has been a regular visitor for the parades – taking to the parade dais as PM David Cameron is expected to do today.