What’s the story

This pink brick appeared in the tunnel under the railway at the entrance to Pollok Park a couple of days. I blipped it as I returned from the opticians with my new reading glasses. I’m curious to know the story behind it.
The most exciting thing this year happened today - an otter was seen in the White Cart in the middle of Pollok Park, and the observant spotter had video evidence. Last year’s young males set out on their own about now and are far less cautious about where they go so I’m hopeful I might just be in the right place at the right time.
Pancakes for lunch which looked a bit frayed around the edges but tasted just fine.