As his predecessor prepared for a legal challenge to his ousting, the Democratic Alliance's (DA's) Daylin Mitchell took his seat as the newly elected speaker in the Western Cape legislature on Monday.

Former speaker, Masizole Mnqasela, filed papers in the Western Cape High Court to challenge his unseating from his position in the legislature and from the party.

The DA had given him the boot over disparaging comments he made about the party and its decisions after whistleblowers handed over evidence to Western Cape Premier Alan Winde of allegedly questionable travel and entertainment claims.

Mitchell, 36, who was the youngest member of Winde's cabinet when he was appointed as MEC for Mobility last year, beat the African National Congress's (ANC's) Nobulumko Degracia Nkondlo 23 to 11.

Leader of the opposition in the provincial legislature, Cameron Dugmore, said the ANC knew Mitchell to be "fair and hard working".

He added: "At the same time, we remain of the view that former speaker Mnqasela did a sterling job as speaker. He was objective and put the legislature on the map."

Dugmore continued, "As the ANC, we had a principled view that the house needed to fill the vacancy. Now that the speaker has been elected, we will give our full cooperation."

DA Western Cape leader Tertuis Simmers said the party was confident that Mitchell would lead the house with "integrity and distinction" after Mnqasela "publicly cessated his DA membership by violating a fedex decision that he should not continue to disparage the party or decisions taken by its structures".

Promising to fulfil the constitutional responsibilities of the house to the fullest extent, Mitchell said in his address that he was "acutely aware of the grave responsibilities bestowed upon me".

"I formally pledge that I shall discharge my duties as the speaker and chief presiding officer of this house in an impartial and fair manner, upholding the dignity and the decorum of this house, that I shall fulfil the obligations placed upon me by the constitution, the law and the rules, regulations and policies of the provincial parliament with honesty and diligence," he said.

"I shall ensure that the process and procedures of the WCPP (Western Cape Provincial Parliament) are fair to all parties represented in this house and maintain a stable workforce serving and supporting all members in their work. I shall ensure that the constitutional responsibilities of the WCPP of lawmaking, oversight over the executive and public participation in the process and work are maintained and, where necessary, enhanced."

Mitchell added that members differed "almost all the time – this is the nature of the beast of parliament".

"However, we can do so in a dignified and respectful manner. Our constituents expect that from us, but they also expect and demand from us a good clean fight in the arena we call parliament."

Winde said his outgoing MEC was an "invaluable part of our provincial cabinet".

"But he now takes on a very important role in our government, which I believe he will fulfil with professionalism. I wish him all the best."

Agriculture MEC Ivan Meyer will oversee the mobility department in the interim.