Paul Pignatelli, Graham Tait and trainee solicitor Hope Donnachie advised on the sale of the majority shareholding, which coincided with the sale of part of Partick Thistle's Firhill Stadium by Firhill Developments Limited, also to Three Black Cats.
Geoff Stansfield and Emma Frizzle of DWF's Glasgow real estate team advised Firhill Developments throughout the property sale process.
Speaking on behalf of the majority shareholders group, David Beattie said: “We are pleased that our hard work in recent months has resulted in this sale. Our aim has always been to secure the future of the Club and we have done this by selling our shares to a man whose support and love for this Club is beyond question.
"Colin Weir undoubtedly has the best interests of Thistle at heart and, although there were alternatives, we believe that his plan to support fan ownership is the most exciting way ahead for this Club."