The Wylex fuseboxes were either rated for the same in each way, with a maximum of 30A.
A few were made with one way suitable for higher current, 40A or 45A, and that was either located directly next to the main switch, or in a few it was an entirely separate one on the opposite side of the main switch (so you might have 6 circuits on the left of the main switch up to 30A each, and a separate 45A one on the right side of the switch.
The difference was the contacts themselves, the high rated being of different material and slightly different design. The busbar was the same throughout.
A few were made with one way suitable for higher current, 40A or 45A, and that was either located directly next to the main switch, or in a few it was an entirely separate one on the opposite side of the main switch (so you might have 6 circuits on the left of the main switch up to 30A each, and a separate 45A one on the right side of the switch.
The difference was the contacts themselves, the high rated being of different material and slightly different design. The busbar was the same throughout.