I couldn't find an online recording by Leslie Sarony. I transcribed the following lyrics from a recording by Albert Whelan found at YouTube:
There was a little soldier who was going off to war. He said, "I know what I'll do when I hear the cannons roar." The sergeant had him on parade; the soldier's not to blame. He went and stuck his bayonet in the sergeant's what's-'er-name.
Bunkey-doodle-i-doh! Sergeant McGinty busted. Bunkey-doodle-i-doh! Gather up all the beets.
He went to see 'em change the guard and said to Captain Squirt: "You don't know how to change the guard; you couldn't change your shirt." He saw a pretty lady 'ome; he'd just come from a dance. A bulldog flew at him and bit a lump out of his pants.
Bunkey-doodle-i-doh! He said, "It's getting draughty." Bunkey-doodle-i-doh! Where do we go from 'ere?
I sang this little ditty to the natives of Madrid. I then sang "Put Me in My Little Bed" and so they did.
Bunkey-doodle-i-doh! Somebody threw tomatoes. Bunkey-doodle-i-doh! Didn't remove the tin.
He said, "If I can't fight, I'll run;" his ruin was complete. The enemy surrounded him and cut off his retreat.
Bunkey-doodle-i-doh! When he got home to Blighty, Bunkey-doodle-i-doh! What did he tell his wife?
That soldier boy has had his day. He's getting old and very grey. He's just begun to fade away. Old soldiers never die.
[There is also a recording by Jack Hylton and his Orchestra which seems to have a few more verses, but the recording was less distinct, so I didn't attempt to transcribe the lyrics.]