From the second half of the 20th century on parties which continued to rely on donations or membership subscriptions ran into mounting problems. Along with the increased scrutiny of donations there has been a long-term decline in party memberships in most western democracies which itself places more strains on funding. For example, in the United Kingdom and Australia membership of the two main parties in 2006 is less than an 1/8 of what it was in 1950, despite significant increases in population over that period.

Why did parties that relied on donations or subscriptions run into problems?