It took me less than thirty seconds to find this.
Labour Party Gerrymandering
It's all about asking the right question.
It's worth noting a couple of points from the article which, although it dates back to 2010, is relevant because since 2010 the Tories have been in power so Labour could not have attempted to interfere with the electoral process since the article was written.
The very first paragraph states that only once has an attempt been made to "interfere with the work of the Boundaries Commission in the last 100 years, and that occurred in the 1960's Labour government.
Now... it's relevant that it was NOT an attempt to actually change the boundaries themselves, but an attempt to "work the system" via the Boundaries Commission. Cynical and wrong, but technically, not gerrymandering. That was (in the view of Jim Callaghan) the beauty of the plan..... no allegation of wrongdoing could be placed at the government's door.
The reason it failed was because the House of Lord's blocked the bill and the subsequent election was contested on the basis of the boundaries drawn up in 1950.
I don't know where Offbeat's memories come from, but if they're unsustainable with some sort of evidence then his recollections can reasonably be discounted.
I spent another thirty seconds of my life asking another right question and came up with this.
Tory Gerrymandering In Scotland
Labour did have to apologise to the Scottish Parliament for not intervening in Conservative Party boundary manipulation in Scotland in 1994. Perhaps that's what Offbeat remembers.....
I'd like to spend longer on this but don't have the time right now. No doubt the deeper I dig the more I'd find but this is something to be going on with for now.
Feel free to add to the list of links and let's see what conclusions we can draw from them.