The organisers of the Cheltenham Festival cited the presence of Boris Johnson at an international rugby match shortly before the race meeting was due to begin in a letter explaining why it was going ahead despite concerns about the Covid-19 outbreak, the Guardian can reveal. There is growing concern at the decision to run the four-day Festival, which attracted more than 250,000 people, after a number of attendees reported symptoms consistent with the virus. Cheltenham Racecourse continues to insist that it followed clear government advice and points out that other major sporting events took place just before and during the Festival. The letter from the racecourse to Cheltenham borough council specifically flags up Johnson’s presence at the England v Wales rugby game at Twickenham on Saturday 7 March – three days before day one of the Festival, Tuesday 10 March. It said: “As with events from England v Wales attended by the Prime Minister at Twickenham on Saturday to 10 Premier League games around the country this weekend, the government guidance is for the business of the country to continue as usual, while ensuring we adhere to and promote the latest public health advice.” The letter, sent just before the Festival began, also quotes advice from the then chief medical officer of Scotland, Catherine Calderwood, who said: “There’s actually very little impact on virus spread from mass gatherings, particularly if they are in the open air.” Calderwood was subsequently forced to resign after facing intense criticism for breaking her own rules to twice visit her second home during the coronavirus outbreak. It went on to emphasise the value of the event to sport and the local economy. “The Festival is of huge importance to the sporting community but also provides significant benefit locally, delivering upwards of £100m in economic benefit to the local community.” Cllr John Payne, who sits on Cheltenham borough and Gloucestershire county councils and chairs Prestbury parish council close to the course, criticised the decision to go ahead. Payne argued the Festival could not be compared with a rugby match. “In the main, people go to the rugby match and then go home. A significant number of people who come to the Cheltenham Festival stay in the area and go into the town.” The racecourse put in measures to try to mitigate the threat including bringing in extra toilets and staff to keep them hygienic and setting up hand sanitiser stations around the course. Payne said: “I don’t believe the extra loos made a scrap of difference. It was a sop so they could say they were doing everything they could.” Trainer Kim Bailey, whose stables are eight miles from the course, defended the decision to press ahead. He said: “I know people who have got the virus Some went to Cheltenham and some didn’t. I think Cheltenham is getting a bit of a kicking for something they don’t deserve to get.” Dr Andrew Preston, reader in microbial pathogenesis from the Milner Centre for Evolution at the University of Bath, said the lack of community testing and tracing meant it would never be possible to know whether Cheltenham contributed to the spread of Covid-19. “But it brought people from all parts of the UK and Ireland together, mixed them up and sent them back home. People were in close proximity, shouting, whooping, hollering. If you had someone there transmitting the disease, there was a very great scope for others to become infected and take it home.” A spokesperson for Cheltenham Racecourse declined to comment on the prime minister’s attendance at the rugby game. The spokesperson said: “The Festival started more than four weeks ago and only went ahead under the clear and ongoing guidance from the government and its science experts throughout, like other popular sports events at Twickenham and Murrayfield, 10 Premier League matches and the UEFA Champions League at Anfield that same week. “We promoted the latest public health advice and introduced a range of additional hygiene measures at the event, including hundreds of hand sanitiser dispensers and extra wash basins.”