In 1767 John Henniker-Major 2nd Baron Henniker (age 14) was admitted to St John's College, Cambridge University [Map]. He graduated MA in 1771 by Royal Mandate.

In 1775 John Henniker-Major 2nd Baron Henniker (age 22) set off on the Northern Tour, that is a tour of the Baltic, commencing at Copenhagen and visiting ports of the Baltic states and Russia. It is suggested that he might have been following in his grandfather's footsteps. He kept a journal of his travels which apparently survives and is held in the archives of a Cambridge college.

In 1777 John Henniker-Major 2nd Baron Henniker (age 24) was called to the bar at Lincoln's Inn.

In 1785 John Henniker-Major 2nd Baron Henniker (age 32) was elected MP New Romney which seat he held until 1790.

On 15 Dec 1785 John Henniker-Major 2nd Baron Henniker (age 33) was elected Fellow of the Royal Society.

In 1792 John Henniker-Major 2nd Baron Henniker (age 39) adopted the additional surname Major by Royal Licence.

In 1795 John Henniker-Major 2nd Baron Henniker (age 42) was elected MP Steyning which seat he held until 1802.

From Jun 1798 until April 30th 1802, John Henniker-Major 2nd Baron Henniker (age 46) commanded a body of infantry, ninety in number, raised for the defence of the parish of Worlingworth, and of the eight adjoining parishes, Southolt, Athelington, Horham, Wilby, Brundish, Tannington, Saxtead and Bedfield. This body of infantry, drawn from the local inhabitants, was called the "Loyal Worlingworth Volunteers" and was prepared to defend their district in the event of invasion by the French.

In 1805 John Henniker-Major 2nd Baron Henniker (age 52) was elected MP Rutland which seat he held until 1812.

In Oct 1810 John Henniker-Major 2nd Baron Henniker (age 58) hosted a Jubilee Feast at Worlingworth Hall in commemoration of King George III's 50 years reign. This was probably the greatest event ever to be staged in the parish. This is how the Ipswich Journal reported the occasion:

The day on which our beloved Sovereign completed the 50th year of his reign, was celebrated at Worlingworth by Lord Henniker with that characteristic loyalty and munificence that had so consistently marked his Lordship's conduct. The day was ushered in with ringing of bells (John Jessop!) and a display of England's proud ensign from the church steeple. The most prominent festivity of the day was an ox roasted whole and afterwards distributed to the populace, in the presence of the Duchess of Chandos, Lord and Lady Henniker and other members of that family. The concourse of people collected to witness this display of ancient British hospitality was very considerable. The number was estimated at between 4 and 5000 but, so ample was the supply of roast beef, beer and bread that all whose appetites solicited them to partake of the feast went away perfectly satisfied. The following lines were written on the bullock being roasted:

Mercy, saith God, is better far Than costly sacrifices are; My Lord both duties has in view, The sacrifice and mercy too; The sacrifice in mercy feeds The poor man who that mercy needs.

In 1812 John Henniker-Major 2nd Baron Henniker (age 59) was elected MP Stamford which seat he held until 1818.