VM
You'll notice when they've gone stereo… the theme tune gets a remix for stereo and the first version is noticeably different. However they revised it so it sounded more similar to the original, before the 1993 version was introduced.
I know we're not far away from the end of EastEnders using the EMI 2001s that dated back to the start of colour. They moved studios in July 91, so presumably that appeared on screen around mid-late August (possibly the same time the show went stereo when NICAM officially started?). Then Top Of The Pops moved into EastEnders' old studio in October.
You'll notice when they've gone stereo… the theme tune gets a remix for stereo and the first version is noticeably different. However they revised it so it sounded more similar to the original, before the 1993 version was introduced.