B-24D 'Silver Streak' 'assembly' or 'formation' ship of 466th BG.
In the views of the later scheme I think the L symbol is made with lights for illumination.
Mechanics undertake their daily inspection of the engines of Consolidated Liberator GR Mark III, FL907, of No. 86 Squadron RAF, at Aldergrove, County Antrim. Copyright Flight Officer H Hensser H – Royal Air Force Official Photographer. Liberator Aircraft at RAF Aldergrove - WartimeNI