I find the current clockworks oddly fitting - with 12 being conceived atop a clock tower

They crept in to the branding and stuck around.

The classic era was also guilty of short-lived title sequences. The first one lasted until early in Troughton's era, then the next one served for the rest of his run. They made a new one for Pertwee, then gave him a new one with the diamond logo when Sarah Jane joined. That lasted one season because he left and was replaced by Tom Baker. His diamond sequence lasted 6 years, before they introduced the neon logo with new music. That one also only lasted a year before he too left. They edited it to replace the Doctor's face. When Colin Baker took over it was more extensively modified, and the music was redone for Trial of a Time Lord. After his firing (meaning that one also only lasted one season), and with advances in technology, McCoy was given a new CGI sequence with another new theme remix. Dimensions in Time used a shortened version of this with no Doctor's face and different music. That one, the TV movie's, and the Shalka theme are the joint shortest lived with one appearance each. Not counting the season 7a logo texture changes.

The Day of the Doctor theme tune was amazing! Pity they can't bring that back and add it to the clocks, which I really rather like.

Like this? ......... http://www.dailymotion.com/video/x25...eme_shortfilms

First time I'd heard that too, just shows how little I care for it that I'd not actively looked for a full version and only just realised I'd never heard the middle eight in the broadcast version.