IIRC, President Trump set HCQ immediately to UK. Boris refused it.
Probably wouldn’t have helped him any more than it helped Trump, who was hospitalized and treated with monoclonal antibodies and oxygen when his SpO2 reached 86%. MABs for COVID weren’t yet available when Boris was sick. For most of us, COVID was a minor illness (I know people in their 90’s for whom it was like a cold), but for some folks like Trump and Johnson, it was potentially life threatening, with or without HCQ.