She’s taller than Nelson’s Column, wider than Pall Mall and more than twice as heavy as the Titanic. P&O’s Ventura is a whopper of a cruise ship.

Launched last weekend, she has a restaurant bossed by Marco Pierre White, a spa, a full-scale theatre, a circus school and bunk room for 3,000 passengers. Yes, 3,000 – but by 4pm on day one, there wasn’t a single berth left on the maiden voyage.

Boutique she ain’t, but busy she is, brimful of amenities designed to make long days at sea pass without boredom. Ventura claims to be the ultimate cruise ship for families – which is why my nine-year-old son Jonah accompanied me on her first jaunt to the Med last Friday.

As befits a maiden voyage, there was a military band on the Southampton quayside, her highness Helen Mirren cracked the champagne and fireworks filled the skies as we edged into the Solent. Compared with the season’s other big-time opening, Heathrow’s Terminal 5, everything seemed to progress seamlessly.

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First impressions? Ventura is as British as sausage and onions, with Boddington’s on tap in the bars and home-grown ship’s officers – one crew member for every three passengers. The interiors are contemporary but restrained. There’s none of the extreme bling favoured by many new ships these days – thank goodness.

There’s lots of open deck and pool space, including an area with a retractable glass lid, so you can still swim if things get squally. The cabins – many with balconies – are particularly impressive, cleverly laid out to give an illusion of space. Or, as Jonah put it: “Although it’s small, it’s actually quite big.”

What catches the eye, though, is the kids’ stuff. With giant Scalextric, an (excellent) circus school, football coaching, a rock school and a resident Noddy for toddlers, Ventura is designed to wow young sailors.

Already, as many as 800 youngsters are booked on one summer cruise alone. And with banded children’s clubs spanning ages 2 to 17, and a night nursery for the under-5s, parents get as much “me time” as they want. There are also lots of all-the-family activities and shore excursions, too.

Food is a big thing on cruise ships, and definitely a good thing on Ventura (apart from the ship’s porridge). Especially fine is The White Room, Marco Pierre White’s first restaurant afloat – not that he wields the saucepans in person, of course. You pay a £20 supplement to eat there, not bad for Michelin-style dining, and you can eat under the stars. There are 11 restaurants in all, including four reserved for family dining, and the service throughout is smart and friendly.

There’s also a breathless programme of on-board activities. You can start the day with a Spinning class at the gym, learn how to remove someone from a digital photo, watch live footie on a big screen, endure a spot of acupuncture or tooth-whitening at the spa, and (on our cruise) spend the evening tittering at Jimmy Carr in the ship’s enormous theatre.

Gripes? Design-wise, it has plastic sun-loungers, and there’s a bit too much Astroturf for my liking. The shops are underwhelming and room service was excruciatingly sluggish.

Nor is Ventura as all-inclusive as you might hope, with extras ranging from drinks at the bar to in-cabin movies, Pilates classes to tips. Prices, however, are reasonable: a bottle of wine starts at £10.50, while a 45-minute Spinning session is £7.

Ventura has yet to be rated by Berlitz, the only independent dispenser of nautical stars, but I’d give her 4½ out of five – we’re talking John Lewis, rather than Harrods or Harvey Nichols.

Would we go back for a proper holiday? An unequivocal yes from Jonah: “Brilliant. Ten out of ten.” If I wanted to cruise without the family, though, I’d opt for a more intimate ship and a wider choice of destinations.

The details: Ventura has summer-long sailings from Southampton to the Med and the Baltic, then visits the Canaries in autumn and the Caribbean in winter (based in Barbados). A two-week Magical Mediterranean cruise, sailing on July 18 to Barcelona, Cannes, Florence/Pisa (from Livorno), Santa Margherita, Rome (from Civitavecchia), Alicante and Gilbraltar, starts at £8,060, based on a family of four sharing an outside cabin. Call 0845 355 5333 or visit www.pocruises.co.uk.

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