Hydraulic Brake Light Switch Replacement, Bleed the Brakes?

This does seem to me like a stupid question to ask, however its always worth checking…

The brake lights on my cabby are not very sensitive to use of the brakes, infact you have to press hard for them to work. Any normal low speed braking does not activate them (kindly pointed out by an angry man in a 4x4!). It passed its mot yesterday like it but its something i need to sort.

I have bought a new switch which has arrived, now since this is plumbed straight into the master cylinder on a brake line port, i imagine i will need to bleed all four corners fully once i have removed the old one and fitted the new?

yep you'll have to bleed the system. an alternative solution is send your switch back and mount an electric switch on your pedal box same as late cabrio and scirocco

I have the same sort of set up as you in my 1978 Mk1 Scirocco and it works fine, the brake lights come on before you feel the car slow down. Do you have a picture of how yours are plumbed in?
 I do have 2 brake light switches fitted to my master cylinder….