Alexander is first mentioned as fighting in the battle of Worcester on the side of King Charles II of Scotland, where he was taken prisoner.
At the Glorious Revolution which followed immediately, Mersington acted a conspicuous part in the attack on Holyrood House, and, according to a letter "to the late king in France" from Lord Balcarres, who designated Mersington the "fanatique judge", Swinton joined the supporters of William of Orange "with a halbert in his hand, and as drunk as ale or brandy could make him".
In July 1690 he was appointed a visitor in the act for the visitation of universities, colleges, and schools,[4] and in June 1698 was elected to sit as president until a question as to the nomination of Sir Hew Dalrymple should be confirmed.
(Swinton 1898, p. 236) Sir James Stewart, lord advocate, wrote of him at the time to Carstares, "He was a good man, and is much regretted".
[6] His wife is said to have joined a mob of women in petitioning parliament in 1674 against Lauderdale's scheme for new modelling the privy council.