Key Points:

Maurice Williamson's erratic political career is on the skids now he has been left out of the new cabinet.

The Pakuranga MP has been in Parliament since 1987 and held several senior portfolios in the previous National government, including transport.

But when National went into opposition after the 1999 election he started running into trouble, or causing it, as party leader Bill English thought in 2003.

Mr Williamson's caustic criticism of Mr English's ability and the direction the party was following sabotaged an annual conference and destabilised the caucus.

Mr English put up with him for a while, but under pressure to deal with the situation he suspended Mr Williamson from caucus.

That lonely life on the back benches continued until Don Brash took over the leadership from Mr English, and Mr Williamson was reinstated.

He was given back his old stamping ground and became National's transport spokesman with a front bench ranking.

But he was in hot water again during the campaign, when he talked about road tolls under National that could be as high as $5 one-way.

Leader John Key had to counter that, saying Mr Williamson had been making "excitable" comments, but Labour seized on it and attacked National.

Despite the put down, Mr Williamson kept on talking about tolls and said they might be $3 a trip.

Mr Williamson is a technology freak and closely follows scientific developments. In 1995 he was made a fellow of the New Zealand Computer Society.

Although he has held his seat with big majorities throughout his time as Pakuranga's MP, he is "old guard" National and Mr Key did not have a place for him in the new look cabinet.

He might also have considered the MP's potential to express maverick opinions and cause problems a new prime minister does not need.

Mr Williamson, 57, was born in Auckland and after gaining a BSc from Auckland University he completed post-graduate studies in computer science and applied mathematics.

He is married with three children.