Circus performers have delivered a letter to Downing Street calling for inclusion in the recent arts rescue package or to be allowed to reopen.
The letter warns that their industry faces collapse in two weeks without government support.
More than 50 acts including clowns, acrobats and dancers from some of the UK's top circuses joined the rally.
Circuses, like all venues, had to pause production of shows back in March due to the Covid-19 pandemic.
'The show must go on'
On Sunday the government announced a £1.57bn support package for arts venues struggling with the negative financial impact of the shutdown.
The bailout included theatres, galleries, museums and music venues and artists, but the Association of Circus Proprietors (ACP) says no provision was made for circuses.
It followed an earlier Arts Council England announcement of a £160m cash injection to help artists, venues and freelancers in the cultural sector but not all institutions qualified, including London's Globe Theatre.
Image copyright Jeff Moore/Borkowski Image caption More than 30 circuses were active in the UK at the beginning of lockdownThe letter from the ACP is supported by 18 member circuses from around the UK representing more than 500 circus professionals.
ACP chairman Martin Burton said: "Sadly, circuses seem to have fallen through the cracks of all the rescue package schemes - we pay rent to individual landowners as we tour - and do not have business rateable properties.
"In addition, no commercial circuses have qualified for the any of the £160m emergency Arts Council funding despite generating significant income to the economy through the 30-plus UK circuses and internationally visiting shows such as Cirque du Soleil which combined are seen by around 20 million people a year.
"Its greatest slogan 'The Show Must Go On' could well become a thing of the past if urgent assistance is not forthcoming."
The Department for Culture, Media and Sport (DCMS) said: "We have announced a major £1.57 billion package to support the cultural and creative sectors as we take steps towards audiences returning to live performances.
"We have developed a five-stage roadmap which provides a clear pathway back for the sector. The next stage of the roadmap will be performances outdoors with social distancing and pilots for indoor events with social distancing. We are working closely with the sector and medical experts on our phased approach."
Image copyright Getty Images Image caption Cirque du Soleil is set to shed up to 95% of its staffPerformers representing circuses including Giffords Circus, Zippos Circus, Cirque Berserk and Circus of Horrors were among those on the march to Downing Street.
Last month, Canadian entertainment firm Cirque du Soleil said is was set to cut 3,500 jobs after striking a deal to avoid bankruptcy.
The group, best known for its flamboyant touring circuses, said the coronavirus pandemic had forced it to cancel shows, including six in Las Vegas, and lay off its artists.
The company is now trying to restructure while shedding about 95% of its staff.
"With zero revenue since the forced closure of all of our shows due to Covid-19, the management had to act decisively," said boss Daniel Lamarre.
Again, the firm had to pause production of all of its shows in March.
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representing circuses including Giffords Circus, Zippos Circus, Cirque Berserk and Circus of Horrors.