HMS Westminster, recently refurbished at huge taxpayer expense, and HMS Argyll will be taken out of action this year, with crews sent to work on a yet-to-arrive new fleet of frigates.
Although the Government wants to cut the size of the Armed Forces, recruitment is still below target.
In 2023, intake at the Navy and Marines fell 22.1 per cent on the year before, while the RAF’s fell by 17 per cent and the Army’s by 15 per cent.
The Navy currently has 26,330 personnel.
The Ministry of Defence has ordered eight Type 26 frigates, which will be the Navy’s most advanced submarine-hunting warships to date.
But the first, HMS Glasgow, will not be operational until 2028 at the earliest, followed by HMS Cardiff by the end of the decade.
Six more are not expected to start arriving until the 2030s.
A defence source told The Telegraph: “We will have to take manpower from one area of the Navy to put into a new area.”