There remains the mystery as to what the other Registration - No. 160987 - referred to ........ you can see from the page you've posted that it was originally for the two numbers.
Presumably the same sort of thing, but different. There were ever so many variations on the theme. Perhaps someday one will turn up, and if I get my sweaty paws on it, you shall hear the details. I'm not holding my breath, though: this is the first St Pancras pavement light I've ever
seen for sale, and I've been looking for years.