The TUC has commissioned a report, "Best Of British".

In it they note:-

"The BBC contributes more than £8bn to the UK economy – approximately £2 pounds for every £1 spent.
For every £1 of income it receives, the BBC invests 56p in the production of original UK content. By contrast, ITV, Channel 4 and Channel 5 invest 44p from every £1. And private broadcasters like Sky invest just 7p.

UK investment in original British television content would be 25-50% lower without the BBC.

....TUC General Secretary Frances O’Grady said:
“Scaling back the BBC would be devastating for the UK’s creative industries and hurt many companies in the private sector."

The TUC Press statement is here.