One way to put a politician on the spot is to ask them how many people have been affected by their policy. Three times seems to be the optimum number of times to ask according to the Andrew Marr’s rulebook as he interviewed Theresa May on Sunday.

Marr asked the question ‘Do you know how man people of the Windrush generation have XX as a result of your hostile environment policy?’ three times to May, each time substituting a different condition into the question frame.

In the first case it was how many people have lost their homes:

Andrew Marr:
d’you know how many people of the Windrush generation
have lost their homes
as a result of your
hostile environment policy

Theresa May: 
the(.)
the Home Office has been looking at all the issue
that have been effecting people from the Windrush generation
...

The second time round it was how many people have been refused NHS treatment:

Andrew Marr:
d’you know how many people of the Windrush generation
have been refused NHS treatment
as a result of your hostile environment policy

Theresa May:
look (.) the (.) Andrew
what we are ensuring
is that those people from the Windrush generation
are being given the help and support
that they need
...

The final time it was how many people have lost their jobs and been unable to get benefits:

Andrew Marr:
d’you know how many people of the Windrush generation
have lost their jobs
and been unable to get benefits
because of your hostile environment policy

Theresa May: 
nye (.) Andrew
what we have been doing
is looking at every aspect
of the impact of people from the Windrush generation
...

External link to clip

In each case, Theresa May avoided answering the question directly and instead stated that they are doing everything they could to help the Windrush generation. Of course, Marr knows that these are difficult questions for May to answer and probably had the answers already to hand. These questions threaten the face of the politician because to answer directly with a number would reveal the extent of the effect of the environment policy that Thresea May was in charge of for several years.

It is said that bad things always come in threes. Andrew Marr seems to believe in this.

BBC, The Andrew Marr Show (about 50 mins)

https://www.bbc.co.uk/iplayer/episode/b0bltt3d/the-andrew-marr-show-30092018