The late 19th century saw an increasing number of wealthy but not aristocratic industrialists who wanted titles (or whose wives wanted them) faster than could be obtained by the traditional route of several decades' service in the House of Commons. At the same time, changes in the election laws (the Corrupt Practices Act 1883 and the 1885 boundary changes and extension of the franchise) made campaigning more expensive. The Liberal Party was in worse shape financially than the Conservatives, so was the first to revive the old practice of selling peerages and other honours- though both parties were already offering baronetcies to men willing to stand in a difficult constituency and spend their own money to do so.

(A baronetcy is not a peerage- while it is a hereditary honour, it did not entitle its holder to sit in the Lords, and therefore did not disqualify him from the Commons.)

The first men to buy peerages in this way were the (Jewish) banker Sydney Stern and the oilcloth manufacturer James Williamson. Both were MPs but had only recently been elected- though Stern had made several unsuccessful attempts. The party agreed that, in return for funds to fight the 1892 election, Stern and Williamson would be ennobled at the end of the following Parliament if the Liberals returned to power. This duly happened in 1895.

Of course, other industrialists had been made peers earlier, like the brewers Allsopp, Bass and Guinness, but the connection between their political donations and their peerages was less clear.

After 1900, the sale of peerages and other honours became more open and blatant, reaching a peak under Lloyd George before the Honours (Prevention of Abuses) Act 1925 made it illegal.

In short, the best way for a wealthy banker or industrialist to enter the Lords was to become involved with the Liberal Party, fight a few elections (and ideally win one), then make an offer to a party organiser such as Francis Schnadhorst the secretary of the National Liberal Federation.

See HJ Hanham, The Sale of Honours in Late Victorian England, in Victorian Studies Vol. 3 no. 3 (1960)