I dunno
based on 2020 it accounts for around 15% of the newspapers sold... and less than 1 in 10 people buy a paper... so something like 1.5% of the population... perhaps on average a couple of people read the paper once its brought... 3% of the population ... i think its the digital footprint and clickbaity nature of its headlines that leads it to it having any impact beyond its very small echo chamber
I believe its currenly selling under a million a day (covid etc) so again whilst its print audience has fallen its probably online it is having an even bigger presence
Circulation of papers has halfed over the last 20 years and its a trend that will continue... the mail has suffered less largly due to the age demographic of readership but fundamentally the 3% of people who pick up the mail reading negative things about labour is not and never will be an issue - its a self selecting echo chaber... a bit like the people who read the canary and are convinced that a youthquake is coming ... the battle is to be had over the people who have little engagement in politics and reaching out to those in the middle rather than trying to battle with people at teh end of a spectrum
That is both interesting and pleasing. At one time it was the leading daily having overtaken the even worse Sun.
And of course there are the online readers who subscribe.
Having said that, it does have a loyal reader base amongst the more right wing voters and definitely has an effect on the way people vote.
I stopped buying a paper a long time ago. Full of made up stories and advertising.
Waste of time and money.