The 16-year-old prince who became George IV did not just quietly fancy one of his teachers at court – he absolutely “esteemed and loved her more than any Words or ideas can express”.

Mary Hamilton’s advantages “in form and person” over other women are eulogised in detail by the lovelorn Prince of Wales in a newly digitised letter.

The revealing, magniloquent letter is one of more than 1,600 records and documents relating to George IV from the Royal Archives published online for the first time.

The material sheds light on the life, relationships and interests of a man once voted Britain’s worst monarch.

Hamilton was asked in 1777 by Queen Charlotte to come to court to help teach the various young princes and princesses. In a letter revealing much about George’s emotional world, dated 25 May 1779, he confides a secret: the name of the woman he is in love with.

“I now declare that my fair incognita is your dear dear dear Self,” he writes. “Your manners, your sentiments, the tender feelings of your heart, so totally coincide with my ideas, not to mention the many advantages you have in form & person over many other ladies, that I not only highly esteem you, but even love you more than Words or ideas can express.”

A love letter written by George, Prince of Wales, who went on to rule as George IV. As a teenager he became infatuated with Mary Hamilton, a lady of the court who was six years his senior. Photograph: Royal Collection Trust/© HM Queen Elizabeth II/PA

The teenage George would often sign his letters to Hamilton with “Palemon” followed by the phrase toujours de même. Palemon was probably from the rural lovers Palemon and Lavinia, a story in James Thomson’s poems The Seasons.

The pair exchanged several letters, but Hamilton managed to resist George’s charms. She instead became a trusted friend and confidante.

Other letters show the consequences of the mental illness of his father, George III. One dated 1789, to the cabinet and Queen Charlotte, argues against Prime Minister William Pitt’s proposal for a limited regency.

It would, he wrote, be a “project for producing weakness, disorder and insecurity in every branch of the administration of affairs, a project for dividing the royal family from each other, from separating the court from the state and thereby disjoining government from its natural and accustom’d support”.

For the last nine years of his life George III was declared mentally unfit to rule and his son acted as prince regent.

George IV is not a man well remembered by history. He is often portrayed as a vain, overspending, shallow idiot, most memorably by Hugh Laurie in Blackadder the Third. In 2008 he topped an English Heritage poll on Britain’s worst monarch.

A letter dated 25 April 1795 does not bathe him in much glory, offering fresh insight into his disastrous marriage to Princess Caroline of Brunswick. Writing only a few weeks after the wedding, the prince expresses his regret that etiquette prevented Caroline’s life from being “more gay and amusing”.

He continues: “If you wish for more of my company, it must strike you that the natural mode of obtaining it is to make my own house not obnoxious to me.” A year later, the Prince of Wales sought a separation.

The documents are published online as part of the Georgian Papers Programme, a partnership between the Royal Collection Trust, King’s College London and various international participants. They include inventories listing thousands of items of furniture, art and decorative arts in Carlton House, his private residence as Prince of Wales.

George IV’s passion for collecting will also be on display in what promises to be a lavish exhibition opening at Buckingham Palace next month titled George IV: Art & Spectacle.