Counter commemorating the Thames tunnel and Trafalgar Square Memorial. Obverse: View of the entrance to the Thames tunnel. Exergue: 'THAMES TUNNEL OPENED 1843'. Reverse: The Trafalgar Square Nelson memorial. Legend: 'ST. VINCENT NILE COPENHAGEN TRAFALGAR'. Exergue: '1843'.

The medal was struck to commemorate two noteworthy projects in London. On the one side is the showy but decorative Nelson's Column, on which the statue of Nelson had been unveiled in 1843. On the other side is Marc Brunel's Thames Tunnel, opened in 1843, nearly 20 years after it was first proposed. The Thames Tunnel was not a commercial success and is little known compared to Nelson's Column, but it was of far greater significance. It was the world's first underwater tunnel, and the principle of Brunel's tunnelling shield served as the starting point for every subsequent tunnel project.