Oil can?

[Nick]

"PSC" may well be the old "Petroleum Service Corporation" who have been around since the 1930s... they may be same as the Petroleum Service Company?

https://petroleumservicecompany.com/our-products/

"NTGB" could indeed be North Thames Gas Board, or even Near-Total Gastric Bypass. Who knows ?

NTGB (the gas company) was founded in 1949, so it might well be them...

NTG is also an abbreviation for nitroglycerine , which is an oily liquid