Mary is off to join the Navy onboard one of its most powerful warships, the HMS Defender, to learn how they turn out hundreds of meals a day against the clock and on a tight budget. Whilst the crew run a war-training exercise on board the ship, Mary heads to the galley to see if she can help the kitchen team with the mammoth task of prepping, cooking and serving 240 meals from scratch in just 75 minutes. Known as ‘action messing’ Mary is really cooking against the clock. In her own kitchen, Mary creates dishes inspired by her experience at sea - a tempting crumble fish pie, special cauliflower soup and moreish mini sausage rolls.

• Mary Berry