Hats off (or maybe scarfs off would be more appropriate) to a Who fan called Chris, who's the creator of
this website dedicated to the Fourth Doctor's neck-warmer.
Depending on your point of view, this is either impressively detailed or terrifyingly anal. We're gonna plump for "impressively detailed". It includes detailed patterns for each version of the scarf, and advice on how to make them (down to what's the best type of yarn to use). Christ, my mother was lucky the internet didn't exist when I was a kid. She was able to get away with a vague approximation of the scarf. If I'd have had this I'd have disowned her for getting one stripe slightly the wrong shade of brown...
Even hardcore Who nutters will learn something. We didn't even know that there were three different versions of the classic scarf (by "classic" we mean "not that burgundy chenille abomination from season 18", obviously). And did you know that they sewed two old scarves together for season 16? We didn't.
Chris, we salute you.