David Bouchier of Olswang drew up the contracts for the UK's biggest broadcasting sponsorship: Cadbury's £10m backing of Coronation Street.
Sponsorship of TV is burgeoning as programme-makers seek extra funds.
Bouchier said Granada had been involved in other sponsorship tie-ups, but the arrangements had been drawn up by in-house lawyers because the deals had never been quite so big or so complex.
Bouchier had to draw up the terms of the sales promotion agreements as well as the contracts for the sponsorship deal.
Because the regulator, the Independent Television Commission, does not allow sponsors to show products on-air, the credits show only a Plasticine Coronation Street that was developed by Wallace and Gromit creators Aardman Animations.
The deal also involves a range of off-air promotions.
Cadbury's wrappers have objects from the chocolate street on them and viewers can match the object on their wrapper with one shown in the TV credits to win a prize.