Around June 1943, a colleague of Brighty, Lieutenant Colonel George Witheridge of the Royal Tank Regiment, arrived at Lulworth. A veteran of the North Africa campaign, Witheridge had experienced first-hand the one-sided battles between British tanks armed with 2-pounder guns against Rommel's formidable tanks and anti-tank guns. During the Battle of Gazala in mid-1942, Witheridge had been blown out of his (US supplied) M3 Grant medium tank, and though he recovered from his wounds, he was declared unfit to return to combat duty. In January 1943, he was posted to Fort Knox in the United States for six months to advise on gunnery, where he was "sold" on the Sherman tanks. While at Lulworth, Witheridge inspected the A30 Challenger, and "joined in the chorus of complaints" about the tank. Upon looking up Brighty and learning of his attempts to use the Sherman, Witheridge lent his assistance. He advised Brighty on methods to solve the recoil issue.