SPDT switch or AND gate: security light wiring

I inspected our security light and found that it had two live wire connections: the red wire on the right and one of the two brown wires on the left. In fact this wire has a brown sleeve over a yellow wire. The cable in is 4-core not 3. It took me a long time to figure it out. It's wired like a landing light combination. The motion sensor on the light fixing is one switch but there is an override switch below that just turns the light on regardless. Here's a wiring diagram for stair lights:

The switches are called Single Pole Double Throw SPDT switches. Double throw because they can make the bulb come on whether up or down but depending on the state of the other switch. For the security light, the two wires between the switches are the 2 live wires. Then there are neutral and Earth wires making 4-core. I don't think the switching is quite identical to the landing light switch because the override switch turns the light on regardless of the sensor. But when the override switch is thrown the other way, the light only comes on when the sensor switches. That mode has two switches in series so acts as an AND gate. Both override switch AND sensor have to be on to make the bulb come on.