Hi Quelch, I bought a replacement key from ebay ; https://www.ebay.co.uk/itm/Replacement-Remote-Key-Fob-4-Button-314-3MHz-4D-Chip-for-Toyota-Alphard-2005/331576219346?epid=841823142&hash=item4d337b96d2%3Ag%3Aq7UAAOSw87RaqM28&fbclid=IwAR3u9ufypXYFlv1pKU1IG7llXfGsIYaK1lLtfLpD_3UqN0KkAIpkxPVc2Sg
programmed the remote easily, using instructions off off the net, and bought a Toyota Smart Keymaker to add the new key to the car ecu.
You can get the key cut at any reputable heel bar. Cost in total , about 40 quid. PM me if you need more info