In the British general election of 2017, "Lord Buckethead" stood in the constituency of Maidenhead. Buckethead is a pseudonym. I understand Buckethead's identity is not public knowledge:
Buckethead, a self-described “intergalactic space lord” whose real name is unknown, won 249 votes in the Berkshire contest. https://www.theguardian.com/uk-news/2017/jun/09/lord-buckethead-elmo-and-mr-fish-finger-a-very-british-election
How / why is it permitted to stand for election under a pseudonym? Usually you see the candidate's full name and address on the ballot paper.
How have the electoral authorities confirmed Buckethead is eligible to stand for office? Do they know Buckethead's name in confidence?