My 56 plate cooper park lane has the puncture detection system button by the handbreak, I know about the activation of it after each presure check but how does it actualy monitor the tyres i cant find any sensors.

Hi

Tire pressure monitoring is carried out by diferentatal wheel speeds. This is calculated buy the cars computer. when the is a difference between wheel speeds of a set pecenage it will trigger the system.
If you set you tire pressures to spec then reset your monitor system this sets the datum this also puts you traction control and stabilty control in to learning mod.
There is no need to do this every time you check or reset the pressuress.

Hope this helps

Thanks for that all interesting stuff