Surrounded by older buildings, Lloyd's Register of Shipping isn't as in-your-face as Rogers' other landmarks.
Lord Rogers and his practice are the proud originators of "sod you" architecture – in the admiring words of former RIBA president Owen Luder. So, it is curious that the latest City offspring of his partnership's famous Lloyd's building should be such a bashful beast.

Just a couple of blocks away from the 1986 Lloyd's of London, Lloyd's Register of Shipping stands as the core of a City block tightly encircled by Edwardian stone buildings. Even from the pavement in front of the main entrance, it is easy to miss its strikingly modern 12-storey tower. Only the odd glimpse through an arch or street corner reveals those tell-tale Rogers features – irregular glass towers and external wall-climber lifts picked out in blue and yellow.

This uncharacteristically shy modern building is the product of the City planners' love/hate relationship with new development. As one of the world's superstar architects had been appointed to redevelop the register's offices alongside Fenchurch Street Station, you would have thought that the City fathers would have stood back and basked in the reflected glory of this reinvigorated generator of wealth and employment.

The City's conservation officer, Tony Tugnell, however, had other ideas. He insisted that an undistinguished and unlisted Edwardian building in front of the main entrance be retained, rather than inserting the glazed entrance block that Rogers had designed as a suitably transparent prelude to the glazed tower behind.

"Retaining the stone building cost us £1m, and it has such shallow floor plates that we can't even use it for offices," sighs an exasperated Michael Warner of project manager Insignia Richard Ellis. "And then, when we'd nearly finished construction, the City planning committee admitted they'd made a mistake."

The cramped site has had an inevitable effect on the office interiors. Except for the upper floors, the offices feel hemmed in, and even the entrance hall and atria lack the liberating sense of space than the practice's recently completed Daiwa building on London Wall has.

Otherwise, the 38 000 m² building has much in common with the Daiwa building – not surprising, as both were designed by Graham Stirk, a Rogers senior director. The double towers have a similarly sleek appearance to Daiwa's, and contrast with the more unruly composition of external ductwork and columns of the Lloyd's building.

The plan form is also similar to that of the Daiwa building. The office space is divided into seven narrow parallel bands that are only 10 m deep and alternately long and short. But the outer band of offices facing Lloyd's Avenue on the north-eastern flank occupies a pair of Edwardian stone buildings.

The office complex was built for £56m by Sir Robert McAlpine, with Anthony Hunt Associates as structural engineer, Ove Arup & Partners as services engineer and AYH Partnership as QS.

Despite completion nearly six months late, staff at the register are about to occupy one of the most state-of-the-art office blocks in London, air-conditioned by an energy-saving combination of displacement ventilation and chilled beams. They will also be the proud occupiers of a secret Richard Rogers classic that unfolds only after you enter a private courtyard that was once a churchyard. What it lacks in sod you architecture, it gains in architectural surprises, bringing a venerable tradition of City townscape bang up to date.