@BigAlastair 

First, the top red LED indicates that you do not have an internet connection which leads me to believe you might have both routers misconfigured for operation with you ISP.  I do not know anything about your provider, but I would imagine you should be configured to use Dynamic IP on the Internet (WAN) setting and do not clone MAC address.  I would check those first or consult with your ISP for potentially different requirements.

If your devices can connect to the routers wirelessly, I would say the above is your first troubleshooting step.  Also, make sure firmware is up to date and perhasps factory reset one and try to reconfigure.

Hope this helps. 

  @BigAlastair 

My local provider came yesterday and checked everything their end and everything works a it should. They also checked the TP-Link Archer and found it not receiving any signal

So it's broke.

I wonder if I will ever get a replacement.