Law began his first round at Close House with five straight pars but then birdied the next five holes in a row, produced a brilliant up and down from thick rough to save par on the 11th, and went on to birdie the 12th and 13th.
The resulting seven-under-par 64 left the 29-year-old a shot ahead of Oliver Fisher, Garrick Porteous and Renato Paratore, with 2018 winner Eddie Pepperell among those two shots further back.
The European Tour has resumed behind closed doors due to the coronavirus for the forseeable future.
All players, caddies and officials were tested for COVID-19 before travelling to the venue and again when arriving on site, with no reported positives so far.
Face masks are required indoors and social distancing measures observed.
“I felt a little bit violated I must say,” said Fisher of the nasal swab test.
“It felt like he was trying to find my brain in there somewhere.”
Law had missed five cuts in seven events in 2020, including four in a row before the sport shut down due to the pandemic.
“I did not really know what to expect,” Law said. “You need to know it might not go your way this week. It’s only one round but it’s a very positive start.
“It was guilt-free time at home because there were no tournaments on that you were missing to be at home. It was a strange time but I got time at home with the family; we have a 19-month-old daughter and we’ll never get that time again.”
Despite the lack of crowds, Pepperell had one particular viewer in mind when he recovered from a slow start with four birdies in six holes from the sixth.
“I think having TV cameras there was a bit of a God-send,” Pepperell said.
“When they’re there, you’re aware you’re on television. My mum’s watching, so I want to impress her.”
One of the most impressive rounds of the day came from former US Open champion Michael Campbell, who admitted he was “completely flabbergasted” with an opening 68.
Campbell has not made a cut on the European Tour since 2013 as he struggled with a foot injury and loss of form, but the 51-year-old New Zealander rolled back the years with the help of his caddie, his 21-year-old son Thomas.
“My expectations were pretty much none,” Campbell said.
“I wanted to get out here and enjoy myself with my son Thomas. When I had my success from 1999 to 2005 he was only seven, so he can’t remember.”
Tournament host Lee Westwood ended the day six shots off the lead.