Myson Apollo boiler: No pilot light.

Hi,
My Myson Apollo 30B boiler now longer works. There's no pilot light. While holding in the gas button I don't hear a hiss like my dodgy memory suggests I did last time I lit the pilot light some years ago. Pressing the spark button doesn't visibly do anything and no pilot flame ever appears.
I've a call out to an engineer, but am I right in thinking that the thermocouple is only concerned with keeping gas flowing once the pilot's lit so it wouldn't be relevant here? Any typical faults, e.g. gas pipe blocked, that may cause these symptoms.
Thanks,
Sam.
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On our Thorn Apollo (is this the same company?) you can usually see the spark through the window when pressing the ignitor. And yes, the pilot light heats up the thermocouple which then keeps the flame in - if it is knackered then the pilot just goes out when you release the gas button.
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In an earlier contribution to this discussion,

I don't know your particular boiler, but I would make the following general comments.
Your pilot light is not lighting either: * because no gas is coming out of the pilot jet when you press the button, or * the spark is not working to light it
I would not necessarily expect you hear the gas, but you may be able to smell it. [If it's a room sealed boiler, get an assistant to sniff around the flue while you hold the button in]. If there is no gas, it implies that the pilot jet is blocked with a lump of crud.
I would have thought that you would see some evidence of a spark if there is one - particularly if you do it in the dark.
If gas *is* coming out, but the the spark is not working, you *may* be able to light the pilot with a long taper - but not if it's a room sealed boiler.
As you rightly imply, the thermocouple only serves to maintain the gas supply to the pilot *once it is alight* - so that is not an immediate suspect.
--
Cheers,
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