From the Wikipedia page 
Museum Lane runs between two of London's leading museums in South Kensington, namely the Science Museum to the north and the Natural History Museum (formerly the Geological Museum) to the south. It runs to the west off Exhibition Road through a gateway connecting the two museums. Opposite is the Henry Cole Wing of the Victoria and Albert Museum.
Museum Lane provides disabled access to the Natural History Museum. During the Exhibition Road Music Day there is a Museum Lane stage as part of the festivities.
The postcode is London SW7.