Are those holes legal under Improved Production rules, anybody been through the scrutineering process with them???

It's very simple to mark the hole centres out carefully with a tape measure, then drill 4mm, 8mm, 10.5mm and then use a hand-held hydraulic hole punch, set up with a 16mm dye. Punch all 5, then throw in the bigger shaft and punch them all at 50mm.

These punch sets are used by switchboard manufacturers, sheet metal fabricators etc

The holes wont be swaged but it's a much cheaper option