Take no notice of 411A. If he knows what he's talking about he's hiding it in a very cunning manner.
Having flown the Twin Otter for about 1000 hours in the right seat both abroad (Africa with a Swiss Licence) and UK (for Loganair) I applied to the CAA (UK) for an MCC exemption, and was granted one when my employers provided a letter to confirm that all training and operation had been as two crew. The CAA actually wanted 500 hours of 2 crew operation.
By contrast, the Swiss wouldn't, despite the same confirmation from the Swiss company.
But I believe that had the operation been single pilot (pilot and assitant) neither would be eligible.
Also, surprisingly, the CAA didn't charge for assesment or issue of an MCC exemption. So, in short , a phone call or visit to the Belgrano would be well worth the effort.