An estimated 400 Mongrel Mob members will descend on a paddock in Te Aute today to celebrate the gang's 50th anniversary.
They will be doing so with a low-alcohol beer in hand after a special liquor licence for a pub beside the paddock was approved by the Hastings District Licensing Committee yesterday.
Police alcohol harm prevention officer Sergeant Ray Wylie said there would be a lot of disappointed people if the celebration did not work out, as the Mob had come a long way to apply for the licence.
"There are the obvious benefits to having the Mob celebrating in one area rather than bar-hopping; it will make it much more manageable for the police.
"If it goes badly we'll be disappointed that the promises made in the hearing weren't kept to, but we're optimistic."
Mr Wylie said Te Aute Tavern licensee Ian Morse was aware of the risk as he had put his livelihood on the line.
"He has faith they won't cause him to lose his licence."
Mr Morse's pub had its licence suspended three times after failing purchase operations, the most recent being in 2013.
The special licence was granted in spite of opposition from police, Hawke's Bay District Health Board, and the Hastings District Council liquor licensing inspector.
The committee said they acknowledged the event would go ahead with or without the licence and therefore focused on the purpose and object of the legislation specifically minimising harm and being reasonable.
The Mob planned to visit eight Hawkes Bay cemeteries in a motorcycle memorial run before convening in a Te Aute paddock behind Mr Morse's Te Aute Tavern.
While Hastings has long been considered the birthplace of the Mongrel Mob, gang scholar Dr Jarrod Gilbert said there was no firm evidence to the myth.
Mr Morse also has to ensure the undertakings set out in the application are observed.
These include a one drink per serve policy, a minimum of five Maori wardens in attendance, and a maximum of 400 people at the event, with entry by ticket or invitation only. Water, non-alcoholic drinks and food are to be available.