They are both one shot ahead of the 2013 title-winner, Ann Lewis (Royal St David's) and two in front of the defending champion, Julie Brown (Trentham).
Laura Webb, who lost to Gertie McMullen (The Island) in the final of the Irish Senior Ladies close championship earlier this year, was the first player in Irish golf history to complete a title hat-trick of the Irish girls championship, the Irish women's championship and the Irish senior women's championship.
Laura would have started the second round of this 54-hole event with a clear lead but for running up a double bogey 7 at the long 18th. Earlier, she had birdied the short second, the short 10th, the long 11th, the long 12th and par-4 14th in halves of 36-35. She bogeyed the ninth.
Webb was a member of the Ireland squad who won the European senior ladies' amateur team championship in Poland a few weeks ago.
Minna Kaarnalahti had halves of 34 and 37, birdieing the first, eighth, 12th and 13th. Bogeys at the 11th and 14th prevented her from breaking 70.
Ann Lewis had five birdies and four bogeys in her one-under 72 (37-35). She birdied the short second, sixth, short 10th, long 212th and 15th.
Julie Brown could hardly have been steadier in her solid start with a par 73. She bogeyed the second and had a birdie 4 at the long seventh. She parred the other 16 holes.
Gertie McMullen (The Island), runner-up in this event 12 months ago, has left herself a lot of work to do to get in contention this time round. She had a 79 today with no birdies and halves of 39-40.
Fog delayed the start of the day's play until just after 8.30am but once it lifted the temperature was touching the 80s.
CSS 75 - Round 1 - Wednesday 14 September