The regiment portrayed throughout this series is an armoured regiment. That is plain from the WWI tank on the cloth embroidered cap badge. But a real regiment, set in this modern, time frame, would have the Queen's crown surmounting the laurel wreath encircling the tank. This would not be permitted, so a nondescript design was used in its stead.
Derek Riddell (Adam Gettrick) & Daniel Ezra (Daniel Reed) also worked together on Undercover (2016) as Paul Brightman & Dan Johnson respectively.