According to Newsweek:
Prince William has been accused of “poor judgment” after allowing himself to be linked to the campaign to keep Scotland in the United Kingdom.
The Scottish National Party (SNP) have been attempting to gain support for a second Scottish Independence referendum after falling one seat short of an outright majority in recent elections…
Against that backdrop, Prince William…[met] with former U.K. Prime Minister Gordon Brown, who has launched a campaign to keep Scotland in the union.
The move sparked criticism from Alex Salmond, …head of the pro-independence Alba Party.