Regarding your article “A Taxation Anomaly which Survived the Budget.” it states that “The horse-power tax was imposed initially in 1910.”
Perhaps you may be interested in the following extract taken from the em>Lady’s Magazine for March 25th. 1776.
“By a new Act for granting to his Majesty several duties on coaches, and other carriages, an additional duty of 20s. per ann. is laid on all coaches, except Hackney. After July 5th. 1776, Stages are to pay a duty of £5 per ann, each, notice to be given and payment made agreeable to Act 20 Geo. II, Clause in the said Act exempting persons from paying more than dye carriages repealed.”
London. S. Eng.
A. F. Anderson.