Towcestrians extended their lead at the top of South West One East to 14 points thanks to a fine 34-3 home win against Oxford Harlequins last weekend.
Tows knew they faced a tough test against a team that, historically, has caused them problems.
Playing with a howling wind and driving rain at their backs it was important to get off to a fast start, but it was the visitors who took the lead through a penalty.
From then on though, it was to be Tows’ day.
James Falvey levelled things up with a penalty before No.8 Craig Holton made the most of some scrum power to dot down.
Tows then stepped it up a notch, with centre Ben Roe the next to score, helping the home team take a 22-3 lead at half-time.
And Tows continued to step on the accelerator after the interval as a moment of brilliance from Yuill saw the left winger outpace the defenders to score in the corner.
The hosts then defended superbly, with man of the match Peter Gowler to the fore, before sealing the game with Alex Chalcraft scoring after good work from Yuill.
Tows now have a sizeable lead over second-placed Salisbury with seven games to go.
After going through in both of the County Cup competitions, the strength of the squad will be tested during the run-in, starting on Saturday at home to Windsor in the league.
Meanwhile, Tows IIs continued their domination of local sides with a 58-5 mauling of Market Harborough.
In the Referees Cup, Tows Colts drew 10-10 with Old Scouts, with Tows progressing to the next round having scored two tries to Scouts’ one.
Old Northamptonians 5 Scunthorpe 48
Tim Cardall scored for Old Northamptonians, but they were well beaten at Scunthorpe.
Cardall dotted down in the second half, but his side had been hampered by three sin-binnings as the home side’s pressure told.
Meanwhile, Old Northamptonians IIs suffered a narrow 17-13 defeat in their merit table game against Ampthill Extras.
Dan Odita and Andy Orbinson scored the ONs’ tries, with Kieran Murdie adding a penalty.
Casuals 19 Dunstable 5
Casuals knew they would have a tough game against Dunstable, who had put 51 points on local rivals BBOB two weeks before.
But the Northampton side eventually emerged winners, leapfrogging their opponents in Midlands 3 East South in the process.
Captain Glen Bradbury touched down early on after some good hands and interplay through the backs.
And it wasn’t long before Craig Naighborough added a second score, with Niall Lawrence on hand to add the extras.
The Casuals pack was firmly on top and a third score arrived before half-time, with Oli Butel scoring.
Dunstable did manage to dot down in the second half, but they were well beaten by that time.
Every Casuals player impressed, with Johnny Schuman, Ryan Hancock and Al Stephens producing particularly eye-catching performances.