New Bearmach igntion switch, what wire goes where?

[rob2640]

I have bought a new ignition barrel and switch for my Defender 90 1990. It has a 3.1 Isuzu in it. The old ignition switch is a Lucas, whereas the new one is from Bearmach and I connected it as it was to the Lucas and it's wrong. Could you point me in the right direction? I have three wires: big brown with large spade, big white, and red and white. There is also a brown and red but that wasn't connected  My new ignition switch is the one attached. 

The old lucas is also attached

[Litch]

Easiest way would be to use a meter and check which contacts connect to what at each of the positions on your existing switch and then check that the new switch operates the same way.
The trouble is that different models use different switches and if your vehicle has had the switch changed at some point (to suit the different engine possibly) then how do you know you have bought the correct replacement?

Although probably not relevant to this query, a perfect example of the differences in ignition switches is in the glow-plug operation.
On early vehicles the glow-plugs were operated by manually holding the switch in the "heat" position for however long was required however on later models this was done automatically by the timer relay so there was no need to hold the switch in that position.