The line is due to restart operations with a series of itineraries around the British Isles starting on Britannia from 27 June and then new ship Iona from 7 August.

This season will run until 24 September when Britannia will begin western Med itineraries on 25 September, with Iona sailing on Atlantic coast itineraries from the same date. Ventura will then resume service with Atlantic islands cruises from 3 October.

But P&O has now cancelled all 2021 itineraries on both Arcadia and Aurora with the ships now not due to begin sailing again until 2022. Although the line plans to unveil a new itinerary on Aurora "with winter sun appeal".

Meanwhile, Azura will begin Caribbean fly-cruises from 10 December 2021 – later than previously planned.

The line’s vaccination policy will also change from 25 September after the completion of its UK cruises. From that date until 31 December, all guests aged 18 and over will have to have completed their Covid-19 vaccinations at least 14 days before departure.

Those aged below 18 will need a negative PCR test within 72 hours of travel unless they have been fully vaccinated within 14 days of travel.

All passengers will also have to take a PCR test which will be provided for free at the cruise terminal.

The line’s policy for UK cruises up to 24 September remains the same: all guests must have completed their vaccination programme seven days before sailing or 14 days pre-departure if they have had just one dose of a vaccine.

P&O Cruises president Paul Ludlow said: “We are very much looking forward to getting Britannia and Iona back to sea for the series of UK coastal cruises - staycations at their best - which are certainly proving very popular and then beginning our international restart as we phase in each of the other ships.

“The current situation means that while unfortunately there will be a number of cancellations of itineraries on some ships, we are looking ahead and planning for the future with vigour.

“We are confident that destinations will soon open up their borders both for UK travellers and also for cruise ships. Spain and its islands and the Caribbean are both looking very positive and we are seeing, one by one, countries publicly looking forward to welcoming us back.”