CAB is one of the many acronyms learnt on The Knowledge; this one is the aide memoire for three bridges spanning the Thames at its wealthiest location: Chelsea, Albert and Battersea, and one – Albert – is arguably London’s prettiest and most feminine. Except for Tower Bridge, built in 1894, Albert Bridge is the only Thames road bridge in central London never to have been replaced.

Built by R. M. Ordish in 1873 Albert Bridge (note: it’s never referred to as The Albert Bridge) is coming to the end of a major restoration project. As well as structural damage caused by traffic, the timbers underpinning the deck were being seriously rotted by the urine of dogs crossing it to and from nearby Battersea Park. Now re-painted pink and strung with fairy lights the adjacent cabbies hut must be one of the most romantic locations in London for a Cabbies Green Shelter greasy spoon cafe.

The unusual construction, and you are going to have to bear with me on this one, has three spans and what’s known in engineering circles as a straight-link suspension system. Each half of the bridge is supported by wrought iron bars attached to the top of the two highly ornamental towers. Meanwhile the side girders along the parapets are suspended, making the bridge an odd mix of cantilever and suspension.

On the south side is evidence of the bridge’s early revenue stream, a small hexagonal toll house, a rare survival and the only bridge left with one anywhere in London. But for me the best thing about this, my favourite bridge, is the sign affixed to the toll booth.

Suspension bridges have an alarming tendency to sway to synchronised movements, known as “synchronous lateral excitation”, a modern example was a little over a decade ago when the Millennium Bridge opened and a pronounced wobble was produced by pedestrians when they walked across the newly opened bridge, nicknamed the wobbly bridge this was rectified by dampers. For Albert Bridge the only modifications has been the suspension members which were overhauled by London’s sewers architect Sir Joseph Bazalgette who in 1884 overhauled the suspension members.

Which brings us neatly back to the sign which local well educated wags have altered giving generations of schoolboys hours of mirth.

“All troops must break step wind when marching over this bridge”.