Adding timer to outside lights with existing pir sensor.

[mikeh6630]

I have 3 outside lights controlled by one pir motion sensor. There is no other switch for them, nor a plug/socket of any kind, the circuit is connected directly to the mains. I want to add a timer to the circuit so they come on and stay on for a couple of hours till midnight, then the pir takes over.
I have just managed to renew the pir sensor, so am sort of familiar with the actual wiring.
Can anyone suggest the simplest way to add a timer. And maybe suggest a simple inexpensive timer please?

 

[ericmark]

It depends if you have a neutral or not at switch position, and if there are enough wires for a switched and permanent line.

 

[Murdochcat]

It depends if you have a neutral or not at switch position, and if there are enough wires for a switched and permanent line.

The OP does state that there is no switch for these lights

 

[mikeh6630]

There is no switch in the circuit. From what little I've gleaned from research, it seems simplest to put the timer switch in parallel. And to use a single pole (no negative or earth) type of timer switch. But that's where I get out of my depth!