A walking tour of Greenwich might just take you back to another world

WE'VE taken an early morning ferry up the Thames and stumble across The Old Royal Naval College, on the first leg of our walking tour of Maritime Greenwich. Although the exterior of the Sir Christopher Wren-designed building is impressive, we turn down a 90-minute guided tour of the building. We do, however, s eek out at least four of the 10 main attractions of the site, which include Wren's twin domes with their gilded weather vanes and the spectacular Painted Hall, decorated by James Thornhill and said to be the "finest dining hall in Europe".

We then visit Queen's House, situated in the same vicinity and tick the box, before bypassing the Cutty Sark, which has been a resident at the dry dock in Greenwich since 1954. The printed hand-out will have to suffice. The Cutty Sark is the only tea-clipper still in existence and boasts a visit to every major port in the world when on commission in the tea industry.

It's a balmy September morning, unusual for London, and we're walking under a brilliant blue sky. For a moment we're distracted by an antiques-and-food market, hidden between buildings, then we brace ourselves for the long hike up to the Royal Observatory, one of the most significant sites on our list.

Halfway up the steep incline we're rewarded with a clear view of London in the distance and at the top we glimpse the Thames as it snakes towards the Millennium Dome.

We discover that the Royal Observatory is not only home to London's only planetarium and refracting telescope, but it also houses Greenwich Mean Time and the Prime Meridian of the World - longitude 0º, making it the official starting point for each day and each year, a fate established in 1884 when an international conference decided that the Greenwich Meridian passed through the observatory.

After ticking another box, we start our descent to the town, which sits on the waterfront of the longest river in England. Retracing our footsteps, we suddenly notice an area cordoned off at the back of the Old Royal Naval College.

Curiosity and intrigue drive us forward and we're just in time to see the cameras start to roll, capturing actors in dark top-hats and tails dashing through the street, almost hidden by horse-drawn carriages fleeing out of the frame.

Suddenly, a siren pierces the air and the hobos - who are in a crumpled position on the stone steps of the building - take flight.

They are joined by fleeing bustled women who, despite their narrow skirts, seem driven. One of the vanguard of the herd, a grey-haired extra, in black top hat and tails, who does little to hide his limp, crosses our path.

"My hip's playing up," he says.

"What's happening here?" I ask.

"It's Sherlock Holmes 2." "With Robert Downey Jnr as Sherlock and Jude Law."

"Were you in Sherlock Holmes 1?" I enquire.

"Yeah," he says. "Many of us were."

I immediately scan the crowd to get a glimpse of director Guy Ritchie, but he is not part of the fleeing mass.

My eyes follow the herd to a tent erected on the far side of the green in the shade of large trees. I almost expect to see Holmes himself outside, smoking his pipe.

As we walk past the entrance, we see the cast standing around, eating lunch out of white polystyrene containers. Somehow it seems incongruous in this 1892 setting.

Dianne Stewart is an author and freelance journalist. Sherlock Holmes: A Game of Shadows is presently showing at local cinemas