[moc] Avonside Engine Co. 0-8-0t transfer locomotive

Despite looking pretty robust for its time, these two 0-8-0Ts were actually constructed in 1866 as transfer locomotives for service between King's Cross and subsidiary local terminals. This meant a lot of tunnel travel, which necessitated the fitting of condenser apparatuses - a resolution that has never really been wholly successful for steam. While this was an era before cab roofs were common, it seems bizarre that the engines didn't have any kind of protection, and I assume crews must...