On Thursday, 31 October 2019 16:50:01 UTC, nightjar wrote:
On 31/10/2019 11:08, Dave Liquorice wrote:
On Thu, 31 Oct 2019 09:26:48 +0000, nightjar wrote:

Meters have always been replaced as their calibration periods expire.

In theory, ours are dated 1967, 1980 and 1996... The two digits in
the first part of the meter number are its calibration year....

I thought that was the year of manufacture and that calibration status
was shown by a sticker.

Meter removed were cleaned, new jewels fitted and recalibrated. The sticker shows either date of manufacture or overhaul.