Avro Lancaster Mk.II - British users, part one

The Avro Lancaster Mk.II was a development of the regular Lancaster Mk.I that was powered by four Bristol Hercules engines. It wasn't very widely used, but some squadrons of the Royal Air Force and the Royal Canadian Air Force used it.
Regarding the ones of the Royal Air Force covered by this post:

• No.115 Squadron RAF: The Lancaster Mk.II replaced the Vickers Wellington in March 1943 and these served with the squadron for just one year, until March 1944, when they were replaced by the Lancaster Mk.I/III as they were reporting better operational results.
• No.514 Squadron RAF: Just when this squadron was formed in September 1943, the received the Lancaster Mk.II at RAF Foulsham, in Norfolk. They began operations one month later, in November 1943 when they were rebased to RAF Waterbrigde, in Cambridgeshire. Their Lancaster Mk.II were gradually being replaced with Lancaster Mk.I/III during the summer of 1944 as they were better.

Sources:

1. https://en.wikipedia.org/wiki/Avro_Lancaster

2. https://www.raf.mod.uk/history/bombercommandno115squadron.cfm

3. https://en.wikipedia.org/wiki/No._115_Squadron_RAF

4. https://www.raf.mod.uk/history/bombercommandno514squadron.cfm

5. https://en.wikipedia.org/wiki/No._514_Squadron_RAF

6. Signal Squadron - Aircraft In action 52 - Lancaster in Action