B-24 from 856 BS/492 BG

[Peter S]

Piece of advice needed. On this picture (sorry - quality in not good but I had to make it smaller because of attachment requirements) B 24 from 856.BS can be seen - 5Z code plus typical black stripe on a tail. (should be also "G" on it but because of the trees and poor resolution cannot be visible). I'm curious about those white or black and white stripes. There are two others Liberators on the left hand side: one from 445.BG and 389.BG behind, but without stripes.
Two different razorbacks: one with and second without stripes. Could someone let me know when, where and on which occasion this picture was taken? Number of people and motorbikes is unusual for normal, operational day.
Regards