there is a brief description of the sinking of Mona's Queen in the book "King Orry" 1913-1940" by David Handscombe (isbn 1-871947-81-2)
sailed from Dover early moring 29th may under captn A Holkham with cargo fresh water - approached dunkirk abt 5.30am abt a mile from harbour hit a magnetic mine which broke her back, ship rolled over and sank within 2mins - 24 dead mainly from engine room (17 manx) 32 rescued many badly injured (two lifeboats had been lauched + luckily a destroyer Vanquisher nearby picked them up)