Front brake discs replaced - but why are the brake lights on?

So my very tolerant “glamorous assistant “ generously allocated several hours this PM to assist with the process of”BLEEDING THE BLEEDING BRAKES”
i grovelled around the 4 corners operating the bleed valves in turn. 
To recap the job centred around updating to 280 mm discs. The opportunity was taken to replace the rear calipers. The front were retained but disconnected for external cleaning before fitting new pads. During that it was necessary to disconnect the pipe from the ABS unit on front left to clean up the end flare. 4 new hoses have also been fitted. At each step with the exception of the pipe to front left calipers the fluid loss was minimal.
So back to bleeding. 
Steady stream from all four corners without bubbles of air when each is bled in turn.
Hosever after releasing glamorous assistant from her duties i see that the brake pedal is well down from its normal position.
I gather I have to remove the brake light switch but sense that this will not be all.
Pressure bleeding is suggested.
To do that I would need to use the spare wheel as the pressure source.
Two questions please
1) what maximum pressure in the spare for this application.
2) when applying the pressure to the head tank and opening the bleed screw at the respective wheel is the foot pedal down, half way down, or at the top i.e. in its normal relaxed position?
 

Im afraid I cant remember 1
but 2= pedal in fully up position

I once pressure bled the MGB clutch system from the slave back to the master cylinder. I can’t think how it was set up now but I do recall noticing that the reservoir cap centre has a disc in the middle. That “blew out” as a bursting disc would on a safety system- presumably to protect the reservoir itself.
So naturally there has to be a sensible pressure limit for the MGTF reservoir. And I speculate that it is only a few PSI and probably less than 10.

(It is surprising what pressure the standard PVC domestic downspout drain pipe will withstand. I never did discover that but it was a lot more than I thought I had applied at the time when using it for test purposes on a wet exhaust heat exchanger!).
 

Thank you all for the various contributions.
I believe I have resolved this with a firm pedal at the top. Perhaps a bit too firm - time will tell.
(Problem was nothing to do with the switch. Just needed to understand what was happening and why the pedal was mechanically preventing the pedal returning).

So on to the next problem.