All of the decisions made in respect of the lockdown are political ones.
Any easing of the lockdown has the potential to resulted in new infections and deaths, but the medical/epidemiological position is only one of the factors that the government has to take into account.
The lockdown carries costs in many ways: adverse effects on mental health, limitations upon the ability to access non-Covid related medical care, children unable to socialise and access full education (with the data suggesting that it is kids from poorer backgrounds who are being most affected), loss of employment and the accrual of debt - the list goes on. In my area of work, the criminal courts are largely at a halt, with an increasing number of people sitting in custody on remand with no idea when their cases might come to trial. And the lockdown will need to be paid for in due course.
The six person BBQ relaxation has no real potential to increase infections, provided people comply with social distancing. Unfortunately, one poll suggests that one in five of the most risky group don't:
https://news.sky.com/story/coronavir...ating-11971794
I don't buy into the idea that the BBQ relaxation is about Cummings. That is now old news beyond The Guardian and Mirror. I'd say it is more about giving people a bit of liberty and encouraging people to get used to the notion that things can and will have to return to something more resembling normality. Someone on the Schools Returning thread talked about Covid being eradicated. That isn't going to happen for years if not decades, if at all.