Prince's tricky Navy service

Defence chiefs and diplomats feared the Prince of Wales might provoke a diplomatic incident in Gibraltar by arriving on board a Royal Navy ship.

When the heir to the throne began military service as a Royal Navy officer in 1971, officials in the Ministry of Defence and Foreign Office agonised over which territories were appropriate for a vessel carrying the Prince to visit.

After narrowing the choice to one of two destroyers in the Far East or the Mediterranean, aides drew up a list of "impractical" countries for the vessels to dock in, documents released at the Public Record Office disclose.

Syria, Lebanon, Israel and the United Arab Emirates were ruled out by the Middle East conflict while the MoD said a visit to the pariah states of South Africa and Greece would hold "embarrassing political implications".

The Prince's decision to join HMS Norfolk, a guided missile destroyer due to leave on a tour of duty of the Mediterranean from Gibraltar, provided Whitehall with its greatest headache.

When plans were drawn up to treat the Prince's arrival on the Rock as an official visit, diplomats warned of a showdown with Spain, still ruled by Franco, despite London's protests that Prince Charles was present as a serviceman rather than as a future monarch. A secret telegram sent from British diplomats in Madrid said: "The occasion would infallibly be taken here as a deliberate and underhand move on our part to reassert our long-term sovereignty over the Rock."

Worried about the fuss Gibraltarians might make, London ordered that the Prince arrive with other crew members in a lorry and that his only contact with dignitaries should be an "informal cocktail party" thrown by HMS Norfolk's captain.