A few years ago one of Nero's enterprising opposite numbers (we don't use harsh words like 'competitor' around here) started an annual celebration we can hardly resist, for today's the day - world Mechanical Pencil Day, to be exact. Because 05/07 might also reference the two most popular lead sizes, 0.5mm and 0.7mm, obviously. Geeky? 'No idea what you're on about.
The history is longer than you might think, and there are some who would argue that a product fairly closely resembling a mechanical pencil was available as far back as the late eighteenth century. But it was in 1822 that the first patent was awarded to an inventor from Taunton, John Isaac Hawkins, who certainly broke free from scrumpy stereotypes - also giving us the upright piano and, momentously, the iridium-tipped nib. The idea of the screw-out propelling pencil grew in popularity throughout the nineteenth century, and you can still buy one from specialist silversmiths if you have suitably deep pockets; Yard-o-Led continue making them in much the same way, using the original equipment for the most part (including when the equipment consists of a Brummie with a hammer).
The mechanical pencil had established itself well by the twentieth century, for obvious enough reasons. Much as many of us like the ritual and aroma wooden pencil sharpening, a mechanism beats that for convenience. So two further varieties joined the club; the basic clutch mechanism beloved of sketch artists, amply mastered by Caran d'Ache, and then the precise ratchet mechanism perhaps most ably executed by Pentel, whose P200 series has been in continuous production since 1970. Rhodia have a pleasantly solid take on that format, if you're interested.
Why wouldn't you want one? Well, the usual complaint is that the HB lead which most mechanical pencils come with as standard is hard, scratchy, unyielding and not much fun to mark a page with. To be fair, there's something in that - but it's very easily solved. For precision pencil-wielders with a O.5mm action there is lead as soft as 4B available now, and it works a treat. Sketchers using fatter 2mm refills can find graphite in an even wider range of grades, and Koh-i-Noor's stock comes highly recommended too. Go on, pick up a clicky!