Gas hob ignition

Hi all

I am doing up a 1998 ford transit autosleeper motorhome
some stuff I am replacing like the water heater and some stuff i am cleaning up and putting back in
There is this oldfashioned lpg gas hob (see in picture)
it is working fine so I am putting it back in for now
However it has presented me with a mystery

the gas controlls work fine but I cannot for the life of me figure out how the ignition is supposed to work
(see pics)
there is no obvious electrical connection
nowhere to put a battery and no friction or piaso ignition that I can see
but yet it appears to have the capacity for spark ignition
I can just use it with a lighter but would anyoun have any idea how this should work?????

https://drive.google.com/file/…sp=sharing
[img][/img][img]gas hob[/img]

As Dave has posted above its more than likely a safety device connected to the thermocouple so if the gas ring is not producing heat it cuts off the gas going to that ring, The heat holds the valve open that allows the gas to flow.........do you have to hold the knob in for a few seconds to get the gas to light?.....if so thats what it is

Thanks lads that explains it
Much appreciated

you keep telling yourself that lol