Several weeks after Martin McGuinness took up office as Deputy First Minister in 2007 , civil servants began asking the Assembly 's Hansard team to replace the capital D with a lower-case d , deputy was spelled this way in the Northern Ireland Act 1998 , the legislation which created the office . Several weeks after Martin McGuinness took up office as Deputy First Minister in 2007 , civil servants began asking the Assembly 's Hansard team to replace the capital D with a lower-case d , pointing out that the title was spelled this way in the Northern Ireland Act 1998 , the legislation which established the office .