Here is a NJ557R Ramsey Sponge Seal from NTG Motor Services in Ipswich, UK. This soft rubber extrusion (sold by the yard) is not as original but may work in place of the Clarke Spares seal (but I haven't tried it to verify one way or the other). It appears that the Ramsey seal (left) will assemble in the same manner as the Clarke Spares seal (right). The Ramsey seal seems to be thicker, but being hollow it may be soft enough to crush into the space allowed around the perimeter of the door similar to the Clarke Spares seal. It may even fill a larger space, which would allow for greater misalignment of the door (in case of poor body repair). The Ramsey seal is available from NTG Motor Services

NTG also has the Furflex seal in black and other colors, and the steel clips> (which may or may not be needed but are recommended by Clarke Spares).