A pleasure

The Serpentine Jack is also one of my favourite patterns. Here are my three IXLs
I also found this one, with the blades almost gone. I was visiting a small village years ago, and asked the owner of a small antiques shop if he ever had any penknives in. He said that he had a couple in his garage, and would find them out for me. A month later, I travelled there again, but he still had not got round to finding the knives. On my third visit, he produced two knives, of which this was the best. I only bought them because I felt sorry for him, but he probably saw me coming
Here's another Serpentine pattern, from the same period
What a beautiful Lobster, and a fascinating piece of history. As I'm sure you know, the crest is that of the City of Sheffield, and I would think that such a prestigious knife would have been made by Ibberson's top cutler, Ted Osborne. It looks like it was made by him too
Even in 1947, the Company of Cutlers in Hallamshire had very few 'cutlers' in its ranks, and even those would have been factory-owners. It is comprised of local bigwigs and 'Captains of Industry', and every year they have a very grand feast. Often, the gentlemen will sit down to find a fine penknife placed before them, marking some great event or a grand individual, such as the Master Cutler or a member of the Royal Family. These were generally made by Ibberson's, and later by Stan Shaw. So, it's possible that your knife is one of a series of knives, but I only raise this as a possibility (the crest is the Sheffield crest, not that of the Company of Cutlers)
Prior to cutlers marking the parts with their initials, the parts were marked with numbers, nown as 'tool numbers', assigned to each worker by the management