The practice of installing lighting circuits without CPC went on for as long as twin cable was available and for a DIYer with a 100m roll it could last forever.
Even more recently it's not uncommon to find T&E used with the 'E' cut short. Example: https://www.diynot.com/diy/threads/loop-ceiling-lights-is-this-correct.648022/
As it happens we had some 7strand 2.5mm² twin made (for loudspeaker use) around 1995 and as we were happy to accept any colours for the conductors and a reduced sheath thickness (To 1.5mm² dimensions) it was a real bargain with some very prominant use of purple.
Even more recently it's not uncommon to find T&E used with the 'E' cut short. Example: https://www.diynot.com/diy/threads/loop-ceiling-lights-is-this-correct.648022/
As it happens we had some 7strand 2.5mm² twin made (for loudspeaker use) around 1995 and as we were happy to accept any colours for the conductors and a reduced sheath thickness (To 1.5mm² dimensions) it was a real bargain with some very prominant use of purple.

