Roads around the 4.25-mile Billown course closed 35 minutes later than planned after heavy downpours in the afternoon, with standing water a cause for concern.

Clerk of the course Giles Olley said the decision was taken to proceed after he spoke to a number of riders, who indicated their desire to complete some practice laps even though conditions were less than ideal.

Ulsterman Dunlop, back in action after winning four races at last month’s Isle of Man TT to become the second most successful rider ever with 25 victories, was second fastest on his Hawk Racing Honda in the wet conditions in the first Superbike session.

The three-time Solo champion completed three laps, setting his fastest speed of 95.158mph, which left him four-tenths-of-a-second down on Manx rider Marcus Simpson.

Jamie Coward was third on his KTS Racing by Steadplan Honda (95.010mph), with Burrows Engineering/RK Racing rider Mike Browne in fourth on his BMW at 94.693mph.

Dean Harrison – who won the Solo Championship race from 2017 to 2019 – was fourth fastest on his DAO Racing Kawasaki at 94.484mph.

However, reigning Solo champion Davey Todd was down in 22nd after running into problems with his Padgett’s Honda machine and pulling out.

Speaking before the session, Todd said: “It’s freezing cold and raining, so fingers crossed the weather improves for the rest of the week.

“But I’m eager to get going around this Southern 100 course and I’ve got the big number one plate this year, so I want to try and hold onto that.

“It’s going to be a tough battle with Dean, Michael and Jamie Coward all so close last year, but we’ll see how it goes.”

There was also a red flag at the end of the first practice session for Supersport B riders.

An incident happened at Church Bends with the rider involved, newcomer Joshua Potts from Stockport, ‘conscious and talking’.

Roads are scheduled to close at 6.05pm this evening for final practice, followed by the first Lightweight and Senior races.