The last Gresley A1 to be built at Doncaster and the first LNER A1 to be named before entering traffic.

At the end of steam, whilst working at Kings cross and out on the line it kept appearing wherever John went.

Isinglass is named after the winner of the 1893 Derby, 2000 Guinneas and St Leger.

Furthe information on Gresley A1/A3 locos can be found in the LNER encyclopedia