Slater, in his first year on the European Senior Tour after surprising himself and everybody else by topping the qualifiers at last October's Tour school, defied a teasing wind and testing course with seven birdies and just one bogey.
"I just can't believe how well I am playing," said Slater, known to his friends as "Big Red" for his ginger hair when younger. When he tapped in for his seventh birdie at the 18th, he set up a new low for the Southampton course, extended to a par 72 for the tournament.
Slater leads by a shot from the 63-year-old former Ryder Cup player Neil Coles, England's David Creamer and the Florida-based Irish professional, Joe McDermott, also in his first year on tour and winner of the AIB Irish Seniors Open two weeks ago.
The tournament incorporates the Professional Footballers' Association championship with past and present players partnering the senior golf professionals. The former Manchester City chairman and England striker Francis Lee led the first day with 40 Stableford points.
In France, Sweden's Marten Olander added a 69 to his opening round of 65 to maintain a one-shot lead in the Challenge de France after another day of low scoring at Sable Solesmes near Le Mans.
Olander is now on the 10-under-par total of 134 but is under a dual threat from Alexandre Balicki and Lionel Alexandre, two Frenchmen who are not regular Challenge Tour members. Balicki carded 68 and Alexandre returned 69 to lie on 135.
Ireland's David Higgins returned a best-of-the-day 67 to move into joint- fourth place on 136, one ahead of the Londoner Daren Lee, who dropped back after a 70.
Sheffield's John Mellor was another to return a 67, which ensured he finished well inside the halfway cut, while Scott Watson and Scotland's Mike Miller were round in 68 to move into challenging positions.
The cut came at two-under with 55 players, including two French amateurs, surviving for the final two rounds.
Among those who missed out were the former Walker Cup men David Park, who was one over the limit after a 67, and Gordon Sherry with 75 for 145.
The former European Tour regulars David A Russell, Gordon J Brand and Steven Bottomley also made early exits.
At Kami, Japan, Noboru Fujiike shot an even-par 71 yesterday and stayed two strokes ahead of Shigeki Maruyama after the rain-delayed second round of the Mitsubishi Galant tournament. A total of 67 players were unable to finish their second round.
Fujiike's round of one birdie and a bogey left him on 131, 11-under.Reuse content