Konta, the British No 1, notched the landmark victory when compatriot Tara Moore retired in the second set of their clash due to a foot injury. Konta was leading 6-4, 3-0 at the time.
A fair number of those career wins have seen the 26-year-old make headlines in the last two years with runs to the Australian Open semi-finals, a defining title at the Miami Open in April and a quarter-final spot at the Rio Olympics.
It was her win over Svetlana Kuznetsova in Rio that she claimed as the best of the 300. “I didn’t know it was a landmark so it is a nice surprise,” Konta, top seed in Nottingham, said. “I was really proud to play at the Olympics for Great Britain in 2016 so that would have to be a highlight and specifically my long match against Svetlana Kuznetsova. Hopefully there are many more to come.”
Watson was not in celebratory mood as she went out to 2016 runner-up Alison Riske in straight sets, losing 6-2, 6-3.
Watson, once ranked 38 in the world, is now down at 113 and will be dependent on either a wild card or advancing through qualifying to play in the Wimbledon main draw.
She is likely to be handed direct entry but does not expect news until the All England Club makes its decision on 20 June.
l The Lawn Tennis Association has appointed Scott Lloyd as its new chief executive. Lloyd, who is the son of former British No 1 and ex-Davis Cup captain John Lloyd, will formally take up his new position in January 2018. The 41-year-old succeeds Michael Downey, who will vacate the role on 30 June after announcing he wanted to return to his native Canada.