The 46-year old world ranked No 2 had not wanted to take part at all, but attendance at the national championships was written in as a condition of his lottery funding package.
He then found himself in trouble in the first race of the day, picking up a penalty in the pre-start, losing the lead when he cleared it with a penalty turn. But he latched on to one of the gusts of up to 25 knots to snatch the result on the final leg.
After that the dispatch was clinical, Williams, still 21 but ranked 33 in the world, finally hit the buffers by incurring two penalties in the final race, but Law said: "The youngsters have really come on the last year." Richard Sydenham beat Andy Green for third place.
Marc Thiercelin, in Somewhere, was last night set to break below the 4,000 miles to go mark on the 6,800-mile first leg of the Around Alone Race from Charleston to Cape Town.
Leader for all of the second week, Thiercelin was making best speed in a total fleet of 16 and had stretched his lead at the top of Class I to nearly 100 miles over second-placed Mike Golding in Group 4.
In turn, Golding has overcome a catalogue of irritating breakages which will require tighter shore preparation procedures in Cape Town before the second leg to Auckland. He has widened the gap over his British rival Josh Hall, third by a further 30 miles in Gartmore.
Hall had seen this and the final Atlantic leg as the two on which he could make most gains from what he thinks is the lightest of the 60-footers. But he is going to need to pick up the pace over the next couple of weeks if he is to establish a cushion for the two legs in the Southern Ocean.
But hanging on hard in Class II's 50-footers is Britain's former SAS officer Mike Garside, who has his Magellan Alpha positioned between class leader Jean-Pierre Mouligne in Cray Valley and Brad Van Liew's Balance Bar.
All three were caught in light airs and Garside feels his swing keel design is slower in what has been upwind work than his water-ballasted rivals. They now approach the Doldrums, which could easily prove to be more decisive.