user: Question: Who was the 1st member with 2nd member Thomas Leigh and was elected in 1557/58?
Columns: ['Summoned', 'Elected', 'Assembled', 'Dissolved', '1st member', '2nd member']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['14 August 1553', '1553', '5 October 1553', '5 December 1553', 'Edmund Mordaunt', 'Thomas Leigh']
SQL:

assistant: SELECT "1st member" FROM "Table" WHERE "2nd member" = 'Thomas Leigh' AND "Elected" = '1557/58';