[1] 1845 he was a member of the committee appointed at a public meeting held in Melbourne on 28 September to frame a petition to the Imperial Parliament in opposition to the proposal of New South Wales to pledge the credit of Port Phillip for an immigration loan for her own benefit.

[3] On 15 June McCombie submitted the following motion to the Council, which was carried by nine votes to five: "That the Legislative Committee be instructed to prepare an humble petition to her Most Gracious Majesty the Queen praying for the removal of Charles Joseph La Trobe, Esq., from the office of Superintendent of the district of Port Phillip on account of his systematic mismanagement of the money voted for the service of the province, his neglect of public works of paramount consequence, and his repeated breaches of faith in his official transactions with this Council in matters of high public importance.

"[3] On 3 August following McCombie presided at a great public meeting held in Melbourne, when a resolution was carried for the despatch of a petition to the Home Government for the removal of La Trobe.

They put the Duke of Wellington, Lords Palmerston, Brougham, and John Russell, and Sir Robert Peel in nomination for the five seats, but in the result five local candidates were returned.

[3] Though McCombie had been one of the most prominent advocates of the separation of Port Phillip from New South Wales, he was not elected to the mixed Legislative Council when in 1851 the colony of Victoria was constituted.