There were many who were skeptical about the efficacy of Molotov cocktails and SIPs grenades against the more modern German tanks. Weapon designer Stuart Macrae witnessed a trial of the SIPs grenade at Farnborough: "There was some concern that, if the tank drivers could not pull up quickly enough and hop out, they were likely to be frizzled to death, but after looking at the bottles they said they would be happy to take a chance." The drivers were proved right, trials on modern British tanks confirmed that Molotov and SIP grenades caused the occupants of the tanks "no inconvenience whatsoever."