4 June – in South Africa, hunter Dick King rides into the British military base in Grahamstown to warn that Boers have besieged Durban. He had set out eleven days earlier. The British Army dispatches a relief force.
16 July – Treason Act 1842 amends procedures and penalties against those threatening the monarch's life.[4]
1 August – Mines and Collieries Act 1842 makes it illegal for women and girls of any age, and boys under ten years, to work underground, following the 1838 Huskar Pit disaster which resulted in the deaths by drowning of 26 children aged 7 to 17.
August–October – first Anglo-Afghan War: British victory at the Battle of Kabul.
7–27 August – riots in and around Lancashire (spreading to Yorkshire by around 12 August), protesting against the Corn Laws and in favour of Chartists.[2]
9 August – the United Kingdom and United States sign the Webster-Ashburton Treaty agreeing the border between the United States and Canada.[5]
Edwin Chadwick's critical Report on an inquiry into the Sanitary Condition of the Labouring Population of Great Britain published by the Poor Law Commission.[6]