He put the decision off initially, but like all those who work the land the lamb's welfare sparked an idea - it was time to talk to the dogs.
"The bleat was still emanating from the culvert, so I selected my two most experienced working dogs, a huntaway and a heading dog, and explained the situation to them."
The simplest way to get the lamb out, he reckoned, was to chase it out with his huntaway, Murphy.
"Murphy knew the lamb was there, his ears were going round and round like radars and his eyes were sticking out on stalks."
But throwing him in the deep pool at the end of the culvert didn't produce results.
"He looked at the culvert, then looked at me: 'health and safety boss, I'm not going in there'."
That left Pip.
"Her entire being is focused on bringing sheep back to me. I threw her in and off she went."
Due to limited room to move, the cast out manoeuvre "wouldn't have earned many points on a dog trial course", yet she worked the animal back to her owner's end of the drain, "where I was able to get a good grip on the lamb's ear".
Perry at this point was still dry, lying head down at 45 degrees on the edge of the drain.
"Pip at this point sensed job done, but the only way she could get out of the water was under the arm that was holding the lamb.
"If you have ever cuddled a soggy doggy, you will understand that I ended up getting wet."
What resulted, apart from one of the best photographs of the year, was "one happy lamb and a heading dog that has no comprehension of what she just achieved".