CQR Brown 0.182mm 12 Core 6 Pair Round Professional Copper PVC Intruder Burglar Alarm Security Cable   £0.45

Proper quality cable, with insulation tear/support fibre; strand insulation which actually strips properly (doesn't stretch and tear like low quality cables) and outer insulation which takes a score from a sharp knife then cracks perfectly when bent.
In short, does exactly what it says on the tin (unlike a lot of cable these days ...).