18 Wheeler- thanks for your response- there were several IR detection and sighting systems in use by all sides during WW2, including the German "Kiel-Gerat" and "Spanner" systems, development of which had preceded the war by some margin.
Indeed RV jones himself carried out the first airborne interception of an aircraft using an IR detector of his own design from Farnborough in 1937.
The blue formation lights mentioned by DY are another possible explanation for these "Resin Lamps"