A VERY young, attractive and winsome woman, that Keira Knightley. Looking at photographs of her was a delight, particularly as they showed her underwater while dressed in formal clothing, not swimwear.

A VERY young, attractive and winsome woman, that Keira Knightley. Looking at photographs of her was a delight, particularly as they showed her underwater while dressed in formal clothing, not swimwear.

Please keep this between ourselves. It's our little secret: there is no reason why Mrs Peggotty needs to know about that little confession of mine. I mean, it was all very innocent, not as if I was deriving any lascivious pleasure from ogling Keira Knightley in that clear blue water, her evening-style gown wafting almost in ethereal wisps.

Another shot - of Keira in the same dress, I am positive - showed her in a balletic pose, apparently suspended midway between the floor and chandelier of an elegantly furnished water-filled lounge. Sharon Stone, also a cinematic siren, featured in another sub-aqua shot.

Rest assured, my interest in Miss Knightley was purely in furtherance of this column, prompted by the caption reporting that the pictures were taken at the Pinewood film studios by Phoebe Rudomino, commercial diver and underwater photographer, of Diving Services UK, to demonstrate a new special permanently-filled tank hailed as “a globally unique water-filming facility.”

I was interested in the figures - no, you misjudge me - not of the Misses Knightley and Stone but of the Pinewood tank, for I had this Porthole-driven impulse to compare them those of the long-gone Great Yarmouth outdoor unheated swimming pool, a much loved part of the resort's summers for over half a century.

The covered studio tank measures 20m x 10m x 6m deep and is permanently full of 1.2 litres of water. In English terms, that is 22 yards long, 11 yards wide and 20 feet deep, containing 263,963 gallons of water - subject to correction if my calculator skills and decimal point placements are found wanting...

So, how does that rate with our old open-air pool, which opened in 1922 at a cost of �14,000 and was demolished in 1979. That was 100 yards by 25 yards, the water depth shelving from 3ft 6in to 9ft 6in at the deep end under the diving boards, and - according to the borough council's official advertisements in a 1948 holiday guide - the basin held “700,000 gallons of crystal clear sea water, filtered and purified every six hours.”

The advertisement proclaimed proudly: “No better water can be obtained for an enjoyable bathe.”

Comparisons are allegedly odious, but we can derive a little satisfaction from the knowledge that the length of this vaunted Pinewood studio tank is shorter than the width of that Yarmouth swimming pool, although the water is deeper, presumably a requirement for building sets that will be submerged for filming. Yarmouth's pool contained almost triple the capacity of the Pinewood one.

Although the Pinewood publicity made no mention of the temperature of the water in which Keira Knightley and Sharon Stone were disporting themselves, I think we can assume that it was heated enough to permit prolonged immersion if a scene required multiple reshoots.

Whereas Pinewood calculated its size to meet filming requirements, our old swimming pool was designed so galas could be held there, hence the race distances of 100 and 25 yards. I suppose that had it survived until now, it would have been useless for competitive swimming which today is over metric distances, and the old 100 yard basin would have needed nearly another ten yards added to it.

But that's all airy-fairy musing...

Despite the unreliability of English summer weather, that pool and its much-loved and sorely-missed Gorleston counterpart were popular with bathers. Crowds of residents and visitors alike used to attend the aqua shows at the Yarmouth pool that were seldom cancelled because of rain, wind or cold, much to the credit and endurance of the performers. At least Gorleston (50 yards long, 16 yards wide) had heated water in its final decade before it closed in the Eighties.

About this time of year, a long queue of schoolchildren would wait impatiently at the Gorleston turnstile to buy season tickets on the opening day of the season, the early-bird head of the line confident of obtaining ticket with coveted number one on it.

There followed a scramble to get changed to be the first to dive into the blue water, often in the low 50 degree Fahrenheit before heating was installed late on. Nobody cared or caught pneumonia: it was all part of the joys of childhood.

As we all know, the Yarmouth pool was removed to enable the construction of the current Marina Centre that also occupies land on which the Marina outdoor amphitheatre stood from 1937. There continues to be a question mark over the future of the Marina Centre that looked like a splendid asset at first, an all-weather, all-year leisure pool with gently sloping “beach” and wave machine, entertainment and catering provision, and facilities for several other sports, all under the one roof.

The biggest selling point for the ratepayers was the official pledge that it could be financed without costing them a penny. How wrong that promise was!

It had not been open for long when we Yarmouth journalists were persistently questioning a Dutch contractor about continuing problems with its (if memory serves me a-right) revolutionary non-chlorine system. Insufficient parking, particularly in peak summer, was another drawback.

Also, potential customers strolling along the Golden Mile in huge numbers in peak summer could not get in for a coffee and to ascertain all that was on offer without having to pay an admission charge, a stupid idea rescinded after public pressure. Then the council farmed out the whole operation of the facility to a private company...

I had a personal interest in the Marina Centre because long-serving Mercury photographer Les Gould and I were on the coach which took borough councillors and officicials to Herringthorpe in Yorkshire to inspect its new leisure complex that became, more or less, the blueprint for the Yarmouth one. I cannot recall any of us on that trip not convinced that it would prove a winner here, but our enthusiasm perhaps proved our undoing.

Now, where was I? Oh yes, those Keira Knightley underwater photographs...