Batting great Kane Williamson says a changed “life situation” will reduce his availability for New Zealand as he prepares for his first international match since March.

Former captain Williamson will take part in the three-match ODI series against England starting in Mount Maunganui on Sunday having been unavailable for New Zealand in any format since they lost the final of the Champions Trophy against India in March.

In that period the 35-year-old, arguably his country’s finest batsman, missed a Test series in Zimbabwe and home T20 series this month against Australia and England.

Speaking ahead of the England series, Williamson said his international availability is limited by a desire to spend more time with his young family, as well as play in lucrative professional leagues.

“As your life situation changes, as mine has, the balance between where you spend your time and give your attention is really, really important,” Williamson told New Zealand Cricket.

“So still being able to play for New Zealand and play the sport that I love at the highest level is great. But the balance is the most important thing for me.”

Since his debut in 2010 Williamson has scored 9,276 Test runs at an average of 54.88 to be comfortably New Zealand’s most prolific batter.

He has gradually reduced his commitments over the last two years, relinquishing the captaincy in all formats.

His “casual” contract with the national body requires him to commit to only certain series and tournaments.

Williamson has spent much of this year in England, where he was captain of London Spirit in the men’s Hundred competition, as well as playing for Middlesex.

He is yet to play under new national coach Rob Walter but has spoken with him extensively about availability.

“It’s just an ongoing communication with New Zealand Cricket and with Rob, and I’m grateful for that,” Williamson said.

“It’s a lot about the balance, with family and time away, but also the delicate balance of being a part of this team that I’ve really loved and enjoyed for such a long period of time.”

Williamson is one of five Black Caps on casual playing agreements with New Zealand Cricket, including Lockie Ferguson, Devon Conway, Finn Allen and Tim Seifert.