The General Blog has some initial thoughts on today's unexpected random selection of historic NPCs, as provided by a vaguely-themed stamp set.
Alan Turing is probably the only one famous enough for a full-on Celebrity Historical, and sure enough I've featured him in The Door In Time and DWM had him star in the comics recently too.
I love M.R. James, made him a prominent part of the backstory of my Cambridge-based Buffy game, borrowed from him liberally here and there and once got a page in The Last Province about him, my sole non-reviewing contribution. In Who terms he'd be an obvious candidate for an "author whose horror stories are true" plot, with monsters guarding ancient relics, as the basis for them was so autobiographical. Of course he also provided the BBC with the basis for most of the Ghost Story For Christmas tradition too.
WWII agent Hallowes is easy to plot for, the architects Pugin and Spence could both be connected in a story about building and possibly what's under buildings, composers like Delius and singers like Ferrier could be involved in music-as-signal mysteries, Newcomen would be a good target for invaders wanting to screw up the Industrial Revolution and Fry's reforms could annoy an alien profiteer. Drawing a blank on Mary Morris though...