The 80-year-old is about to star in Man In An Orange Shirt, part of the BBC's Gay Britannia celebration of the Sexual Offences Act in 1967.
Speaking ahead of the show's first episode, Vanessa told press including Express.co.uk that she was shocked the country was labelled a democracy until then.
"How we could call the cruelty democracy?" she began. "[Characters in the film] have got this cruel and really harsh attitude and of course, we see that in power now, don't we?"
Vanessa hit back at politicians, saying "we can't be silent now" about social issues
Man in an Orange Shirt airs tonight on BBC Two at 9pm
We can't be silent now, everything we have now – we can't be categorised
"We can't be silent now, everything we have now – we can't be categorised.
"We can't do this total, stupid rubbish and this film is an oceanic wave carrying us through all that s**t," Vanessa insisted.
Man In An Orange Shirt, written by novelist Patrick Gale, follows the two love stories, separated by time but linked by blood.
In the first episode, Captain Michael Berryman (played by Oliver Jackson-Cohen) and artist Thomas March (James McArdle) fall in love in the World War Two trenches.
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However, their love is denied and when the pair return home, Michael goes back to a strained life with his wife, Flora (Joanna Vanderham).
The second part is set in 2004 and features a grown-up Flora navigating a relationship with her grandson, Adam Berryman (Julian Morris) who also comes out as a gay man.
The first part of Man in an Orange Shirt airs tonight on BBC Two at 9pm.