Mark was first in the 50m butterfly, 50m backstroke, 100m freestyle and 200m freestyle, at an event kicking off the 2016 West District campaign.
Lanark team manager Mary Kelly said: “I was very impressed with Mark’s efforts considering he had the flu just two days before.
“It was touch and go whether or not he even took part in the competition.
“On the Saturday morning I’d been sitting waiting on a phonecall from him to say that he wasn’t going.
“Mark looked very pale on the day but he was determined to win and the adrenaline kept him going.
“Given his condition, I was surprised that Mark managed to do so well. He was absolutely exhausted after his fourth race.”
In the same age group, Mark’s Lanark ASC team-mate Heather Stevenson was third in the 200m breaststroke.
And clubmate Erin Snow was second in the 200m breaststroke in the 14 years age group.
Mary said: “Heather had a good fight against the other leading swimmers in what was the race of the day.
“It was very exciting because the lead changed hands several times.
“Erin just went out, gave it her all and did very well.”
Lanark’s other breaststroke finalists were Shiona McClafferty (16 and over) – who was sixth in the 200m – and Alistair Dunsmore, who was fifth in both the 100m and 200m events.
Robbie Davenhill (12) and Euan McLeod (11) both competed in a long course pool for the first time.
Robbie was fourth in the 50m butterfly and 50m backstroke and Euan was fifth in the 200m freestyle.
Mitchell Stevenson (15) was fifth in the 50m butterfly and Robyn Patrick (16 and over) was sixth in the 100m freestyle.
Sarah Lang and Finlay Patrick both recorded personal best times.
Mary added: “It was another successful weekend for the club.
“The two youngsters Robbie and Euan did well to reach their first ever finals.
“It was very heartening to see nine Lanark swimmers in finals.
“The next big event for our swimmers is the Scottish Schools Swimming Championships at the end of the month at Tollcross in Glasgow.”