Hello there!
Jago here aka binky on Facebook .

New to me 2017 triton.
Going for a day out tomorrow as tier three and fed up of not being able to use it.

Turned on the gas ( the round know at top of gas canaster) and the valve in the cutlery draw to horizontal, but no gas coming out.
Previous owners told me it was half full.

Have I missed some thing?

There is a tiny knob under what I assume is the regulator.

If you have a small knob on the hoze from the gasbottle, that is a security valve. Close the gas, press the knob and open the the one on the gasbottle. Hold down the knob for 5 seconds. That should fix it. The green one in the picture

t hose.jpeg - Bild entfernt (keine Rechte)

I didn’t see anything, I think there was a black knob under regulator? Have posted on fb as well as easier to upload photos

Where on FB?

Mine is black too. With the control wheel on top of the cylinder fully open press the top of the black "button" and hold for a second or two'. You'll sometimes feel a slight movement as it clicks into its "stay open position"ie as the gas pressurises the line. This is a hose-break protection device: it shuts off the gas supply if the hosepipe from the cylinder to the regulator is cut or punctured.