A shot of the engine bay on both sides would be helpful.
You may want to post over at the Australian forum, there is much knowledge over there.
What's odd, (IMO) is that the ID tag is "pop" riveted on, AFAIK RR (or any other coach builder) never used pop rivets to mount the tags.
It started as a Standard Steel saloon in Tudor/Shell Grey, body number 4505. Original engine B153M, 4.5 L. First owner Allworth Trust Co. Ltd, UK Reg NTU708. First noted in Aus in 2001, owned by a Saunders with reg. 735BYR. Built as a Special by unknown and reg as CYF374. The combination of red and white and the radiator position not altered makes me believe I saw it for sale in Sydney a few years ago with a silly price attached. The chassis plate has been riveted on to a non standard firewall. I would also be curious to see more pics and even the car itself (as I'm just over the border from you)
Hi mate... yep, this was for sale for a ridiculous price($250K). It ended up being used as a deposit on a block of land in SE Qld. I purchased off the developer who took it as part payment.
It appears to be modelled on the Halse vehicles but had to ascertain whether it is a Halse vehicle.