George and Lynne are with a friend called Liz. Lynne looks at a portly man in the foreground. She tell Liz that she knows her well enough to ask about her and Lionel, that he's much older than her. Liz says that he's reached the metallic age; silver in the hair, gold in the teeth – something she's accepted – and lead in the feet. She adds at the end that he is a darling.
This could be George and Lynne's back garden. We know it has a reputation for being overgrown, but this does look more like a wood than their back garden. It could be that they are in a campsite, and the walk from the camping area to the shower is through a deep forest. With all the sticks and stones on the ground, walking in bare feet might not be such a good idea.
Liz had married Lionel, who is much older than her. It has taken Lynne this long to comment on their relationship, which suggests that she did not know them before they were married. For once, someone in Wimbledon has not married an older man just for their money. Liz seems to genuinely like Lionel, which is refreshing.
Liz describes Lionel as having lead in his feet. Initially, it would seem she means that he is quite slow. However from the last frame, it seems that she means his feet are very heavy as he seems to have sunk into the ground. George, Lynne and Liz should help him immediately before he sinks deeper and starts to suffocate. They should also be careful they don't get sucked in themselves. After they have done all this, they should report to the campsite manager that the path to the showers has an area of quicksand so that a sign can be erected without delay.