The couple were described as "prominent and much-loved" figures in their community.
Mr Johnson, elected as council leader earlier this year, had helped organise the town's Christmas market, launched at the weekend as part of a series of festive events.
On Friday he attended the opening of a Waitrose store in nearby North Walsham along with other signatories.
Mr Johnson's close friend, Benji Cabbell-Manners, had been away for the weekend and told the Eastern Daily Press of his "terrible shock" at hearing the news.
More top news
A British violin teacher facing extradition over allegations of abuse has been found dead at his home in the US.
Two actors have been killed after a 'fake' rifle exploded on stage during a live performance of a play in southern Italy.
Kim Davis denies the licences to same-sex couples in defiance of a Supreme Court ruling earlier this year.