By 1832, he had withdrawn from the wine business, and by 1840, he is considered to have sold his majority stake in his East India agency.
In that year's general election, he stood for Hythe and—with the help of a non-existent opposition, money, and patronage of the East India Company—he was "virtually impregnable".
[2] During this period he voted for Catholic emancipation, economy, retrenchment, and reduced taxation, as well as parliamentary reform—and was, in 1824, was described by James Abercromby as having "a very odd temper, which makes it difficult to deal with him".
He was returned for Hythe once more, alongside his cousin and chairman of the East India Company, John Loch, against opposition.
[2] After the election, he requested in an "anxious wish" from the Tory patronage secretary Joseph Planta for James Redsull to be made a Cinque Ports pilot.
Planta noted:[3] Now though Mr. Marjoribanks is a Whig and has as yet voted against us, yet his Whiggery is very much modified (I think) of late, and if he chooses to come forward and ask this as a favour, it would perhaps (if it be a small favour) be a good thing to give it to him.Marjoribanks' request was neither initially approved nor denied and a decision was made to consider this "at the proper time" as there was no appointment of pilots scheduled for that year.
[3] At the 1832 general election, Hythe was reduced to a single-member seat and Marjoribanks was again returned, opposed by a single Tory candidate.