The second light on the front of the boiler shows that it has turned off due to the boiler reaching a temperature above the setting of the high limit stat. There is no link to the boiler control button ie you cannot reset the boiler control by pushing the button on the front of the boiler.
So it seems my problem is definitely related to the high temp thermostat, as all re-starts have been achieved by pressing the reset button on the front of the cabinet.
Strangely enough have now gone since before Christmas without a failure.
Either the problem has corrected itself OR the high temp thermostat is not working at all anymore.