Martin B-26A - British Users

The Martin B-26A Marauder was an improved version of the original B-26 that incorporated the changes made to the production line, including better machine guns in the nose and replacing the 0.3in of the tail with 0.5in ones. Some of them were delivered to the Royal Air Force.
In 1942 a batch of of some B-26A were offered under the lend-lease agreement,  to the Royal Air Force, that designated them as Marauder Mk.I.. Like the previous Martin Maryland and Martin Baltimore they were assigned to the Mediterranean Theatre replacing the Bristol Blenheim of the No.14 Squadron operating from Egypt. They flew the first operational mission with the Marauder on 6th November 1942 and were employed in reconnaissance, mine-laying and anti-shipping strikes. Unlike the USAAF, the Marauders of the No.14 Squadron managed to use eficiently the torpedo-bombing capabilities of the Marauder as they sank various merchant ships with that weapon. It also proved to be efficient against enemy air transports as it shot down various German and Italian air transports operating in the area.
The No.14 Squadron was the only one in the Royal Air Force that operated the Marauder until 21st September 1944 when they were returned to the United Kingdom, where they replaced the Marauders with Vickers Wellington Mk.XIV and were assigned to anti-shipping operations.

Sources:
1. https://en.wikipedia.org/wiki/Martin_B-26_Marauder#British_Commonwealth
2. https://en.wikipedia.org/wiki/No._14_Squadron_RAF
3. Signal Squadron - Aircraft in Action 50 - Martin B-26 Marauder in action.