David Honey, a 59-year-old father-of-six, Alcoa manager and former WA Liberal president, continues the party's unbroken hold on the conservative seat, securing just over 70 per cent of the two candidate preferred vote by the time counting finished on Saturday.

Opposition leader Mike Nahan said he may lighten the load of his own portfolio by handing Dr Honey the economic development or public sector management role.

The latter was "rich pickings" after dramatic amalgamations by the McGowan government slashed the number of public sector departments and agencies.

"He knows a thing or two about the bureaucracy," Dr Nahan told reporters on Monday.

"Obviously I will give him a front bench position."

Dr Honey told AAP he would do whatever the leadership team wanted.

Some senior Liberals MPs wanted a young woman in the seat, backing 40-year-old mining executive and lawyer Emma Roberts.

But Dr Honey suggested he had the edge over other candidates because his experience meant he could "hit the ground running".

That was critical given the party's representation in parliament had been slashed in last year's thumping election loss, which he blamed on state debt and the Roe 8 road project.

Labor did not bother fielding a candidate in the by-election.

The last time the party did was in 1990 when two-term premier Colin Barnett won the Cottesloe by-election.

Dr Honey said the Greens must be "profoundly disappointed" they barely picked up votes that would otherwise have gone to Labor.

Australian Associated Press