NEITHER the public holiday nor the searing heat could stifle the enthusiasm of Ipswich Grammar School faithfuls as they returned to the place where it all began 150 years ago.

The historic school - the first non-denominational secondary school to be opened in Queensland - celebrated the milestone in Grammar's original building, the Great Hall, on Monday.

Governor of Queensland Penelope Wensley was on hand to reflect on the tremendous achievements that had defined the Ipswich institution of the last century and a half.

Ms Wensley was the guest of honour at a small assembly of about 100 current prefects and some Year 11 students, as well as current staff and Grammar Old Boys.

Then Governor George Bowen officially opened Ipswich Grammar on September 25, 1863, and the current Governor pointed out the significance of that moment in history.

Bowen had been mortified by the low literacy rate of Queenslanders in the middle 1800s, and Ipswich Grammar School was to be the beginning of the answer to that problem.

Despite the formality of the event, there was an element of humour to the catwalk of uniforms worn by students and headmasters of the school since 1863.

Current senior student John Massey was an intimidating sight in his grey suit and cane - dressed as long-serving former headmaster Richard Kerr, whose tenure lasted from 1915 to 1945.

A full-school assembly followed the next morning.