Zeppelinstrasse MQ at EDUO had coke boilers in the cellar. The pipework was mostly tarnished copper: tarnished but acceptable at my march in, so there was temptation. Knowing my successor for the MQ, and disliking my successor, out came the Brasso.
At march out the powers that be noted the gleaming boiler room and suggested that the next march out might be rigorous.
My successor never spoke to me again.
As an aside, coke was delivered down a chute into the cole'ole. The old boy had a crude abacus at the back of the cart to tally each sack. It was not unknown to distract the old boy and minus an abacus tally. My children had sooty hands sometimes.
As a civvy who allegedly did not pay for fuel on the mysterious XY scheme, I was always the incumbent when lecky was needed for street lights or Christmas.