A senior Labour politician touted as a future Labour Party leader is romantically involved with the long-time partner of a Kiwi musician debilitated by a severe stroke.

Labour list MP David Parker is said to be involved with Auckland sculptor Barbara Ward, partner of rocker Chris Knox.

Knox, who has been confined to a wheelchair since a massive stroke in June 2009, is best known for the song Not Given Lightly - written for Ward. Knox and Ward have two children, John and Liesha, who are also mentioned in the famous love song.

Not Given Lightly has been voted New Zealand's 13th most popular song and is the country's most-requested wedding song.

The stroke cost Knox his ability to speak, and left him needing fulltime care. Ward is understood to still be involved in that care.

Parker, recently tipped as a possible successor to Labour leader Phil Goff, did not return calls yesterday. He was quoted in the Dominion Post as saying: "I go to public events with her. Beyond that I am private about my private life."

The paper said Parker's marriage to respected Dunedin poet Susan Wootton ended early last year. The couple have three children aged between 11 and 18.

Ward has been actively involved in the Labour Party and worked as MP Phil Twyford's campaign manager in the 2008 election.

Relationship Services national practice manager Cary Hayward said people who had strokes often had a personality change which could leave partners grieving.

Stroke Foundation of New Zealand chief executive Mark Vivian said strokes often had greater impacts than the obvious physical effects. "The hidden impacts of stroke are often more significant for their family members to live with."

He said it was not unusual for stroke victims to experience short- and long-term memory problems. "There's some quite good research that people caring for anyone with a physical disability are more at risk of depression and physical injuries."

There are more than 8000 strokes in New Zealand each year, a third of which are fatal. About half of survivors have significant disabilities which might include personality or communication difficulties.

Stroke support can be accessed at www.stroke.org.nz.