Can you complete Thomas Eaton’s fiendishly difficult Christmas quiz?

Full of festive fun (and/or frustration)• Want to get inside the mind of the setter? Thomas Eaton reveals all here1 Which seasonal figure was murdered by his brother, Boleslaus the Cruel?
2 Why does a Welsh hamlet in the Tywi Valley get extra post at this time of year?
3 A Brit award winner in 2017, which singer’s stage name was inspired by watching Steptoe and Son?
4 Why was “covfefe” in the news in May?
5 What festive item was first recorded in Britain on Cornhill in 144