I sucessfully changed my 4/4 cambelt, a feeling of smug satisfaction.

A few days later I came across a YouTube video, 'How to calibrate your torque wrench'.
https://www.youtube.com/watch?v=XaqBA-xSGbc

Out of curiosity I checked my large torque wrench, 60 - 220ftlbs, which was spot on. However, when I checked my small torque wrench, 10 - 80ftlbs, which I have had for about 10 years, I found it was 'clicking' at a value approximatly 25% below the set value. There are videos on YouTube which show how to reset a torque wrench, so now, it is spot on.

Then I realised I had a problem! My small torque wrench is very useful for the low values required when working on an aluminimum engine and I had used it for the majority of the cambelt change. 10 -15% error I could live with but not 25% when a cambelt is involved. So yes, I took it all apart and put it back together again, with the correct torque values.

The learning point, 'It pays to calibrate your torque wrench now and again'