Colour match

I am new here, so be gentle.
I am working on the restoration of a 1940, 145 ton Steam crane. As part of the resoration the whole vehicle has to be needle gunned to bare metal, primed and painted. As its outside, but undercover and I can only devote one day a week on it, it will probably take about 3 years.

So much for the history, now the problem. We took a part of the vehicle to a supplier, who colour matched it with cards and we bought 5 ltrs. When we tested it instead of being a deep red (like pillarbox) it came out with an orange tinge to it, Ok to see in the dark, but not the right colour.

On a visit to Focus we found a Crown domestic paint called FLAME RED. It is a lovely deep rich red, just what we need, but they only sell it in small tins, and with 145 tons to paint this was not viable. So off to Crown paint suppliers. They said they could not supply this paint as it was domestic but on being pressed said they would get from the paint factory laboratory the formula for this colour, so they could mix larger amounts. This they did, we took it to the crane and did a test piece, and quess what, it was orange red. Nothing like the colour we requested.

I know nothing about paint except you can spill it. Please has anybody any idea of whats going on. Is red a difficult colour to match, and what is it with this orange red that we keep getting. How do we go about getting what we need please.

Any help would be appricated. Thanks