Replacing horstmann 425 coronet central heating only

[Sopre19]

What central heating programmer can be replace the 425 coronet with onto existing back plate without rewiring. Thank you

 

[RandomGrinch]

I believe the Horstmann/Secure ChannelPlus H17XL would fit on the existing backplate, without any wiring changes...

Horstmann H17XL 7 Day Time Switch

Manufacturer Code: H17XL

www.ukhps.co.uk

Although, could we have a photo of your backplate to confirm (isolating the power safely before removing it)?