Royal Mail was forced to rely on a skeleton staff to deliver only “essential items” on Friday after 115,000 postal workers went on strike in the year’s biggest industrial action so far. The 500-year-old postal service’s employees are planning further industrial action for Wednesday next week and 8 and 9 September in a dispute over pay and working practices. Royal Mail workers across Great Britain demonstrated on picket lines in Dunfermline, Hull and Preston, among other places. In east London, striking employees called for Royal Mail’s chief executive, Simon Thompson, to quit. They chanted: “Thompson out” to the beat of drums on the picket line and sang: “Simon Thompson, you’re not fit to be the CEO.” Other collective cries included: “What do we want? Thompson out. When do we want it? Now.” Royal Mail, which employs 140,000 staff including managers, has offered workers a 2% pay rise, backdated to April, and further benefits equivalent to a 3.5% increase if they agree to changes in working practices. Thompson said that deal would cost the company £230m and that the business was losing £1m a day. Executives say the changes are needed in order to grow Royal Mail’s parcels business in the face of intense competition from rivals including Amazon and DPD. The CWU argues that staff should receive a pay rise in line with inflation in recognition of their work delivering post during the coronavirus pandemic. A survey of 2,005 adults by the CWU, seen by the Guardian, showed that 63% of respondents believed Royal Mail should be a public-sector company. Dave Ward, the union’s general secretary, said: “British people have had enough of their country being asset-stripped by the rich. It’s time to bring the postal service back into public ownership.” The strike is the first since Royal Mail was privatised in 2013. The study also found that 72% believed company executives should have their pay capped at 10 times the average worker’s wage. “Right now in this country, corporate failure gets rewarded time and time again, with no consequences for the poor running of services people rely on,” said Ward. Royal Mail said that, during the strike, 379 of its 1,200 delivery offices were processing mail and were staffed by about 4,000 managers and “supported by contract hauliers”. It said their priority was “delivering essential items”, including prescribed medicines, Covid test kits and special delivery packages. A Royal Mail spokesperson said: “Our contingency plans to minimise disruption and keep people, businesses and the country connected are operational.” About 6,000 temporary workers will “assist with our recovery plans” after Friday’s strike, the company said. Royal Mail executives have threatened to split the company if workers do not agree to its proposals. “Without modernisation, we die,” its non-executive chair, Keith Williams, told the Guardian. Thompson apologised to customers for a “disrupted service” during the strike by workers, but said that change was necessary for the company. A fresh twist in the corporate drama unfolded on Thursday when it emerged that the Czech billionaire Daniel Křetínský has hopes to increase his company’s stake in Royal Mail from 22% to 25%. The government is reviewing the move.