The Miners Lamp Collectors Society, in cooperation with Wolf (UK), published a book on Wolf UK safety lamps in 2012. It says of the Type F, "Four original models designed in 1957/58 by William Norman Bishop", and that estimated production of the Type FS from 1959 to 1963 was "10-20 samples for trial". It also says the Type FS was in production 1962-1988, at a rate of about 1500-2000 per year.

The Miners Lamp Collectors Society, in cooperation with Wolf (UK), published a book on Wolf UK safety lamps in 2012. It says of the Type F, "Four original models designed in 1957/58 by William Norman Bishop", and that estimated production of the Type FS from 1959 to 1963 was "10-20 samples for trial". It also says the Type FS was in production 1962-1988, at a rate of about 1500-2000 per year.

..........G.P.O. used them in large numbers from the early 1960's to late 80's for testing in cable ducts.

In fact they were still in use on the BT Deep Duct Laying contracts until 2001 when they were replaced by MSA gas detectors. The main reason for phasing them out was apparently due to some middle managers in BT at the time being recent university graduates with no experience feeling very uncomfortable about taking "naked" flames into a potentially gaseous environment.

In fact they were still in use on the BT Deep Duct Laying contracts until 2001 when they were replaced by MSA gas detectors. The main reason for phasing them out was apparently due to some middle managers in BT at the time being recent university graduates with no experience feeling very uncomfortable about taking "naked" flames into a potentially gaseous environment.

Managers more worried about being sued, HSE getting involved etc. on the offchance there is any gas present and further offchance the lamp manages to ignite the gas, is more like it!