Sheppard and Newcastle's Sue Rolph raced stroke for stroke up the pool in the 50-metre freestyle, with the Glaswegian winning narrowly in a British and Commonwealth record of 25.47 seconds with Rolph, who had herself broken the Commonwealth 100m record 24 hours earlier, second in an English record of 25.50.
Hickman broke his own British 100m butterfly record for the second time in a day, clocking 52.87 to clip 0.1sec off the mark he had set in the morning heats.
Sandwiched between Sheppard's and Hickman's feats was yet another British record set by London's Martin Harris, who lowered his 50m backstroke mark by 0.01 to 26.00 and in so doing booked his seat on the plane to Istanbul for the European Championship this month.
Bath University's Mark Foster, short-course world record holder in the 50m freestyle, won the British long-course title by half a second in 22.74 - just outside his British record.
The women's 100m butterfly title went to the South African champion Mandy Loots, with 15-year-old Nicola Jackson just pipping Georgina Lee for second to add the event to the 50m butterfly already in her programme for Istanbul.
Hatfield's Mark Racher also secured his presence there by beating his personal best by three seconds to win the 200m individual medley in 2:04.98.