The much-anticipated improvements to the long railway tunnel which separates the southern section of Bermondsey Street from Tooley Street and the Thames have been completed.
The transformation has been funded by section 106 payments from the vast More London office development north of Tooley Street.
"The innovative lighting design creates a huge well of light in the tunnel and provides a striking purple wash of light over the parapet," says Riverside ward's Cllr Nick Stanton, leader of the council.
"This has enhanced both the safety and aesthetic value of the tunnel, and will no doubt encourage locals to use the route more often.
"Development and investment around the Thames riverside benefits the whole borough, and this project provides a vital link in that chain."
Over the last 12 months the Bermondsey Street tunnel has had all its brickwork and metalwork cleaned and painted and a new lighting design has been installed.
The colour-changing lights can be programmed to show almost any conceivable combination of colours – so themed displays for particular festivals and events could be possible in future.
The new lighting consumes 40 per cent less energy than the previous equipment installed in the tunnel, whilst still providing more light.
The Bermondsey Street Area Partnership has been campaigning for refurbishment of the tunnel for more than a decade, and BSAP's Michael Davis joined the celebrations on Tuesday, along with representatives of More London, Team London Bridge and Southwark Council.
The work forms part of the Light at the End of the Tunnel programme which has seen railway arches across North Southwark and North Lambeth cleaned and refurbished.