How Many Different Kinds of Pens and Paper Do You Need?

I know that any Procurement that saves £18 Million a year should be a win in any book, but I was just flabbergasted that the UK government needs 3,500 catalogue items in office supplies. Office supplies. Yes, this is much better than the 15,000 they were buying before, but come on, 3,500? One type of pen, one type of pencil, one type of paper, one type of B&W printer toner (because you standardized the printers, right?), etc. Yes, when you iterate through each type of office supplies, it adds up. But I’d have a VERY hard time coming up with 1,000 different necessary items. What’s the other 2,500+ for?