Their son had the right idea....
From watching this, I assume their son and his family lived in London or another large UK city.
It was obvious that said city would be a prime target and that this family could not survive a direct hit, so they spent the time leading to the attack in enjoying what time they knew they had left.
The old man in this film was so preoccupied with past glories of his WW2 service, he spent the time just scurrying about to prepare for something he and his wife could not ultimately survive, but die a slow, painful death rather than a quick end.
Sounds like the son had the right idea about what was ultimately important.