In 1611 John Eyre (age 31) and [his wife] Dorothy Bulstrode Lady in Waiting (age 19) attempted to murder Edward Herbert 1st Baron Herbert Chirbury (age 28) who he suspected of having an affair with his wife (Dorothy Bulstrode Lady in Waiting (age 19)). Eyre (age 31) and four accomplices caught up with Herbert (age 28) and his two footmen at Scotland Yard as he was leaving Whitehall Palace [Map], and wounded his horse several times. Eyre (age 31) broke Herbert's sword. Twenty more men appeared, Herbert thought them Eyre's supporters and attendants of the Earl of Suffolk (age 49). Two other men helped Herbert, and after a prolonged struggle he wounded Eyre, who was carried to the Thames vomiting. A few days later Eyre sent a message that he would kill Herbert with "a musket out of a window". Meanwhile, because Eyre (age 31) claimed Dorothy had confessd to being unfaithful, she sent a letter to her aunt Lady Croke (Note. probably Prudence Croke (age 44) possibly Elizabeth Croke denying this, and Herbert was able to give this letter to the Privy Council. The Duke of Lennox (age 36) said that John Eyre was "the most miserable man living" because of the shame of Dorothy's letter, and because his father had disinherited him on hearing of the assault.

In 1614 John Eyre (age 34) was elected MP Cricklade.

In 1626 John Eyre (age 46) was elected MP Calne.

In 1628 John Eyre (age 48) was elected MP Chippenham.

On 24 Aug 1629 John Eyre (age 49) inherited Great Chalfield, Wiltshire from his father but sold it two years later to Richard Gurney 1st Baronet (age 51).