The following information found at a site dedicated to Wilmon (Bill) W. Worth, JR, who served on USS LST-493.
"On Saturday, April 22, 1944 LST-493 became the Group 28 LST Flotilla flagship per Secret letter Serial No. 50-125-44 dated 21 April and Confidential Sailing Order 50E435 from C in C Plymouth, England. Accompanied by U.S.S. LSTs 17, 30, 47, 264, and 503, the ship joined Task Unit 123.1.1 with L. F. Teuscher, Commander, USN, aboard as C.T.U. At the rendezvous, LSTs 73, 75, 25, 229, and 279 formed into two columns in route to Weymouth. At 2218 the anchor was dropped with other ships in Weymouth Road, Weymouth, England. No bearings or landmarks were available due to total blackout conditions. Several days passed as many other U.S. and British ships dropped anchor near the convoy. April 27, Secret letter 28/A4-3 was received from Commander Group 28 dated 27 April 1944, Serial No. 009. Per orders, the convoy proceeded to The Solent, Isle of Wight, England. LSTs 279, 229, 44, 52, 345, 344, 370, 308, 312, 21, 72, 17, 264, 73, 30, 503, 287, 280, and 25 got underway on various courses and speeds conforming to the channel under Material Condition X-ray, cruising condition III. The 493 passed through the nets to the Solent off the Isle of Wight and let go anchor at 2150. Two days later, 493 got underway and moored at Sugar Two Dock, Southampton, England to take on board 5 officers, 68 enlisted personnel and 32 vehicles of various Royal British Army groups. Included were the 346 Co. RASC Infantry Brigade, 522 Co. RASC Infantry Brigade, 186 Field Ambulance, 8 Durham Lt. Infantry, 9 Durham Lt. Infantry, 25 Lt. A.A.R. Artillery, 120 Lt. A.A.R. Artillery, 102 Anti-tank Battery R. Artillery, 233 Field Co. Royal Engineers, 35 Field Dressing Station, and 980 Squadron 54 B. Flight Balloon Unit.On May 4, the convoy got underway per Top Secret Orders Operation Plan One Letter LST Group 28/A2-11/A4-3 dated May 1, to Hayling Island, England. The 493 was Task Unit Commander for five other LSTs, 344, 308, 287, 30, and 279. All ships were streaming Barrage Balloons on 100 feet of wire rope and were bound for amphibious maneuvers."
I found USS LST-312 listed among Convoy MKS.31.