Boiler programmer wiring

[Rawsox8]

Ok, so im no stranger to basic electrical work, changed a few plugs, rose lights, and even a 3 valve port on a central heating system ha.
I want to replace my old Myson microtimer for a more modern one.
Issue i have is the wiring.
The newer ones have N L 1 2 3 4 E
My current one has N L 1 2 3 4 5 6 E
All apart from 6 is used.
Live is joined to 2 and 5 via a brown cable.
Any idea on how i would wire this up correctly?! I will attach a few pictures.

 

[Timbo]

1 is HW on, 3 is HW off, 4 is CH on.
Refer to the wiring instructions for your new programmer as to which terminals to connect to.

 

[Rawsox8]

1 is HW on, 3 is HW off, 4 is CH on.
Refer to the wiring instructions for your new programmer as to which terminals to connect to.

Ok cool. Which would be ch off then?

 

[Timbo]

6. But you don't have.
Google Horstmann 525 wiring diagram.

 

[Rawsox8]

6. But you don't have.
Google Horstmann 525 wiring diagram.

Thanks you ?