At the beginning of the episode Foggy is pretending to take a potshot at a phone engineer on a telephone pole. Foggy tells him that he reminded of him of a sniper in Burma. He took out a quiet a few snipers back in the day before wondering that he hoped they were snipers and not phone engineers.
Compo is still sore at Smiler living as a lodger with Nora Batty. Smiler has been sent on an errand to buy some spuds and taken a wheelbarrow with him. A squeaky barrow that makes a noise like a bird twitching which confuses Howard and Marina who pretend to be birdwatchers.
Foggy things hills have gone steeper and climbing them has become more difficult. He has persuaded Wesley to develop a chairlift. Which is basically an armchair on some wheels. Of course each time he tests it with Compo, calamity happens. The reason being it is a barking idea, for a start you need Wesley pulling it up the hill with his winch.
As you can guess all three of them on the armchair end up rolling down the hill.