Can’t take much credit for this how to guide. I followed the post on the forum (below) and can confirm that it does work.

Tools/Materials needed:

• Star head screw drivers (large and small head)
• Small flat head screw driver
• 4 core electrical cable
• Cable stripper

Steps to install:

**Make sure power to boiler is turned off at the fuse box and tested**

1. Hook up electrical cable to heat link as shown:

N – Neutral – Blue wire

L – Live – Brown wire

2 – (Common) – Grey wire

3 – (Call for heat) – Black wire