The 2nd ML Flotilla
was based at Plymouth during Operation Neptune
and comprised MLs 112, 113, 114, 116, 117, 119, 120, 171 & 491, with 116 (Albone) & 117 (MacDonald) attached to the 14th Minesweeping Flotilla
The 14th MSF was attached to Force U which was assigned to Utah Beach in the American sector. The starting points for its invasion vessels were Dartmouth, Tor Bay, Weymouth, Poole, Torquay, Plymouth and Salcombe. During the assault phase on the night of the 5th/6th June, the 14th MSF was tasked with creating the swept channel No. 2, and thereafter, the area between channels 3 & 4, and then as required.
This information is derived from the following work, which is largely based on the official Battle Summary.
Naval Staff Histories of the Second World War Volume 1: Operation Neptune, The D-Day Landings, 6 June 1944: Edited by Tim Benbow: Helion Press 2015
This article provides a useful insight into the role that MLs attached to minesweeping flotillas performed, namely sweeping ahead of the minesweepers themselves to help keep them safe, and thereby heading the entire invasion fleet.
Halcyon-Class D-Day Minesweeping
Other possible sources of information include:
National Archives: Operation Neptune