Well, the Anderson shows were always timed to allow for commercial breaks within their 30 or 60 minute lengths, as they were always sold in the first instance to British commercial television. I think it wasn’t specifically to sell to the US that the episodes were bulked up (the 30-minute Stingray had already been sold to US syndication), but because Grade thought that the show was of sufficient quality to sell for more prestigious hour-long slots. He seems not to have been wholly successful in this, as the next show, Captain Scarlet, dropped back to 30 minutes to make it easier to sell.
Well, the Anderson shows were always timed to allow for commercial breaks within their 30 or 60 minute lengths, as they were always sold in the first instance to British commercial television. I think it wasn’t specifically to sell to the US that the episodes were bulked up (the 30-minute Stingray had already been sold to US syndication), but because Grade thought that the show was of sufficient quality to sell for more prestigious hour-long slots. He seems not to have been wholly successful in this, as the next show, Captain Scarlet, dropped back to 30 minutes to make it easier to sell.