I think I just found some photos that match the nose art, Lancaster ED713 from 576 Squadron (Nulli Secundus (Second to None)). Note that 103 Squadron and 576 Squadron both were based at RAF Elsham Wolds and may possibly have even exchanged planes from time to time. ED713 was lost in December 1943.
There are three photos which show the nose art about halfway down the page on this link:
http://aircrewremembered.com/hughes-richard.html
Based on the number of mission markings that are clearly visible in two of the photos, those two were taken some time later in 1943. Your photo was probably taken in the summer of 43 at Elsham Wolds. Note the photos enlarge if you click and "hold" on the image.