A video posted on Facebook by the Bridge Folk Club of a rather stirring rendition by Cohen Braithwaite-Kilcoyne (click) matches the following text, from Rhymes of the Rail by F. W. Skernett (1920), pp. 23-28 (link) at first blush -- I didn't listen and compare exhaustively. The Facebook post credits the tune as "Tramps and Hawkers," with Dallas still as the source point. Florence Brunning's Folk Song Index also lists the tune as Castles In the Air (Bonnie Jean o' Aberdeen), as you said above, which bears the tune for Tramps and Hawkers. The lyrics from Skernett's book are as follows:

THE FIREMAN'S GROWL
(With all due Apologies)

It's not all beer and skittles, this blooming job of mine,
And it's not a bed of roses, isn't firing on the Line.
You don't get too much money, you get lots of slack instead,
And they teach you how to work at night to earn your daily bread.

Just fancy being knocked up in the middle of the night
With a noise enough to wake the dead, give the neighbourhood a fright;
You leave your bed with sad regret, prepare to catch your train,
Then a chap comes round to tell you you can go to sleep again.

And when you do get to the sheds, that's when the fun begins,
For someone's pinched your spanners and lamps and other things.
You know it's not quite up to Rules, still you like to do the same,
So you take someone else's and pretend you've played the game.

You often get an engine that is very shy for steam,
And it's then you start to realise that life's not quite a dream;
You get quite a "fed-up" feeling when the Driver tells you that
"We're losing time," and then you lose your temper and your hat.

Then he starts to be sarcastic, and you swear there'll be a rup.,
When he asks you "Do you think you've put the coal on right side up?"
He suggests you get your Jimmy, then you give a silent groan,
As you suddenly remember that your Jimmy's safe at home.

It's lively in the tunnels when you slip, and then you stick,
And the air mixed with the language gets beautifully thick;
The smoke it nearly blinds you, and with sulphur you near choke,
You turn to get a drink and find your blooming bottle's broke.

Of course, it's not expected that we chaps want much to eat,
But now and then we get a chance, and it really is a treat;
When you've put your food upon the floor, it's enough to raise your ire,
Your mate gets absent-minded like, and drops it in the fire.

And when the stick's at danger, as sure as you're alive
There is a Rule made by some fool, they call it fifty-five.
You've got to walk perhaps half-a-mile, through snow, or hail, or rain.
You sign a book, then sling your hook, and tramp it back again.

Well, you reach your destination, neither happy, blythe, nor gay,
With just strength enough to whistle "End of a Perfect Day."
All your hopes are fairly stranded, when the Turner says "Book-off"—
Miles away from home you're landed, neither money, 'bacca, scoff.

They send you to a barracks built inside the Station Yard,
Where the engines sing your lullaby, and the beds are nice and hard;
Or, perhaps, it's private diggings, they're another lively hole,
For it's ten-to-one the blooming fire's gone out to find some coal.

You go to bed half famished, and pretend it's for the best,
And say "when the stomach's empty the brain will get a rest."
But it's fairly aggravatin'—just about chills you to the bone,
When they knock you up to tell you you've to work the "Diner" home.

You start the homeward journey, and things reach a pretty pass;
When you're half inclined to envy the cattle out at grass,
And you vow you'll chuck your job up, you swear you'll do no more.
Reach your home: "Come on in nine hours," and the game starts as before.

It's a shame they work the Drivers till of age they nearly drop;
Why can't they have a pension, like a postman or a "slop"?
They earn it, they deserve it, and then contented they would be;
Besides 'twould mean promotion, and there'd be a chance for me.

I often wonder if I'll ever get a Driver's job,
For I'm sick and tired of firing sixty hours for thirty bob.
Perhaps I'll fire until I die, and then to heaven I'll go—
Or, perhaps, I will be firing still for the Old Lad down below.