Underground sign meaning?

[busboy75]

I wonder if anyone knows what this sign means? A chap is selling this and believes its from the underground but he is puzzled at the meaning and so am i!!

 

[Merle Haggard]

There were vaguely similar signs at stations on the Euston outer suburban lines - I recall one at Bletchley.
The difference was that the lower part could be switched, by a moveable cover plate, between displaying 'on' and 'off'.
Those were an instruction to guards to switch the heating on AM10s on or off. Changed over about April and October generally.

 

[busboy75]

I thought it may mean heating but thought i would sound ridiculous lol! Thankyou so much you are very knowledgeable!

 

[philthetube]

They certainly were on the underground, however I Thought that they were placed on the entrances to tunnels.

 

[Dstock7080]

They certainly were on the underground, however I Thought that they were placed on the entrances to tunnels.

indeed, at stations before/after long tunnel sections on LU

 

[3141]

There were some just west of Arnos Grove in the 1950s. My understanding was that they conveyed instructions about the heating. I seem to recall that what they displayed didn't always accord with what common sense suggested they should.

 

[Central]

Heating wasn’t supposed to be on in tunnel sections,don’t know if that’s still the case.

 

[3141]

Heating wasn’t supposed to be on in tunnel sections,don’t know if that’s still the case.

In line with that, the sign for westbound trains should always have been H OFF, as a reminder that they were about to enter a tunnel. For eastbound trains, in the winter months it should have been H ON, and H OFF at other times. My memory now is somewhat hazy about what these signs were displaying 70+ years ago, but as I said, I seem to recall that what they showed wasn't always what you would have expected.

 

[whoosh]

I thought it may mean heating but thought i would sound ridiculous lol! Thankyou so much you are very knowledgeable!

The old trams in London - Inspectors made hand signals to Conductors to open windows by however many inches, or all shut, or all the way open. It was very military based with orders passed down, and little letting on the ground staff think for themselves.
I dare say the Underground was similar.