From the factory most of the interior structure would be aluminium coloured. This includes the inside of the wing, gun bays and wheel bays, and fuselage. The canopy framework and often the interior cockpit framing would also be painted aluminium, only the cockpit panels would be in cockpit grey/green. Cowling interiors, inside of radiator intake, also aluminium.
I've seen it claimed that the interior cockpit framing on the Mk II was painted grey/green, not aluminium, but in the pilot notes for the Mk II it is clearly a much lighter colour than the surrounding panels which I believe means it was still painted in an aluminium colour.
Areas like wheel wells and inside of gear doors might get over sprayed in an underside colour if or when the aircraft was re-sprayed on its wheels (same applies for other types) but that was not factory standard.
I don't know the provenance of that rather obviously posed picture of KZ295. It would be interesting to know where it was taken. I have my doubts that it was taken at the original point of production. If it was, then clearly at least one factory was spraying inside gear doors and wheel wells in the underside colour on tropical Hurricanes.
Anyone who can postitively identify a difference between grey, light blue or aluminium paint (not bare metal!!!) in a B+W photograph has got better eyes than me
I have less evidence for Canadian built Hurricanes, but what I have seen implies that a similar method was employed. I have been told that the Canadians used Zinc Chromate in some areas, which was not the case on UK built aircraft.
Cheers
Steve