As Chris.ac states, there are more than 1 ECU involved.

It is the immobiliser bit that is tricky.

 

I have a key without any buttons or innards, the 4D67 chip is included in the key blank (if you get the correct one) has been matched to the car.

It starts the car; without ANY issues with the car. This is the key I use daily with the attached remote smart key.

 

Timpsons did cut my key, but I had the car there to ensure the key fitted the ignition but It didn't start the car.

Timpsons did not programme the immobiliser chip. I had to find an Auto Locksmith willing, and able, to do that part.

I have this problem, lost the spare key to gen 1 alphard can find the key no probs on e.bay, but nobody wants to cut it, i have a working key

There is an association called The Auto Locksmiths Association. I have used one of their memebers in South Gloucestershire. They are not cheap mind but doa fantastic job in my view. They have a member down your way. Check out his link.

 

https://jwlocksmith.co.uk/vehicle-key-replacement/?gad_source=1&gbraid=0AAAAAqXKpd1-Bc0GlRRpMm8NphZtZxOfe&gclid=CjwKCAjwwLO_BhB2EiwAx2e-30Jn-9cIMHIzezLc77jsbofQw8N6kNpnladrc7B5DxcTW3WVICOtdhoCluAQAvD_BwE