I just took a scheduled flight with BIH to the Isles of Scilly and back (Sikorsky S61), one of many down the years.
There is no curtain and the flight crew sit somewhat aloft, providing a great view of ops. It was an absolute treat to sit in the front row and appreciate the high workload these guys face. The taxiing procedure is fascinating; forwards, backwards, sideways, or all three according to the subtleties of the wind. This unique service is now under real threat and they appear to be down to just a single machine for operations, so I urge all cockpit-view fans to get down to Penzance PDQ.