Johnson holds multiple pitches at all the big meetings and having endured a quiet few months due to the wet winter, was hoping for a change in fortune.
However, the British Horseracing Authority's decision to suspend racing, initially until the end of April, leaves the on-course bookmakers among those unable to gain any sort of income.
"The current restrictions on racing will have a major impact on my business and that of many other bookmakers," said Johnson.
"I fully understand the reason for the suspension of racing, but this could not have come at a worse time for on-course bookmaking. After a very wet autumn and winter with many abandonments, bookmakers required a good spring to help their cash flow.
"Taking Doncaster as an example, we lost the last two major meetings of last (Flat) season and now the first major fixture of this season. We were lucky that Cheltenham went ahead, but business was considerably down on a normal year.
"Many bookmakers are small, family firms with no other income. Many will have borrowed significant sums to purchase pitches and to fund working capital and those costs have to be met.
"Many of the staff have no other income and as many are self employed, there is little or no Government help. My own costs, fixed and staff, will exceed £20,000 a month whilst there is no racing and this cannot be sustained indefinitely.
"On-course bookmakers are a fundamental part of the race day experience and it is hoped that this is recognised by the Government, the Levy Board, the BHA and the racecourses and that they will all see fit to offer financial support - not only during the period whilst racing is suspended, but also when racing resumes.
"Amounts paid to racecourses over recent years has increased much, much more than inflation and now is the time for a generous gesture from them and the other bodies to help the industry."
It is a similar story for the off-course firms.
Betfair's Barry Orr said: "As with so many industries, the economic impact of Covid-19 and its ramifications will be felt throughout every aspect of the racing community.
"From a bookmaking point of view, Flutter (parent company to Betfair) CEO, Peter Jackson, has already said that if the current situation were to continue into August, then it could impact the Flutter Group to the tune of £90-110m.
"With racing in the UK now cancelled until the end of April, that will also have a significant effect on turnover. "
Michael Shinners from Sky Bet said: "Obviously, like so many industries, this is a testing time for both bookmaking and horse racing. However, we fully understand and support the BHA's decision."
Nick Rust, the chief executive of the BHA, said: "There will be difficult months ahead for many of us. We need to focus now on ensuring that we can continue to look after our horses as the virus affects the thousands of participants and staff who dedicate their lives to caring for animals.
"We need to do what we can to support businesses inside and outside racing and the many people whose livelihoods depend upon this £4 billion industry.
"We are in constant contact with Government which understands the very significant consequences of this decision for jobs and businesses. We will work with them to do our best to manage the impact.
"Racing leaders will keep today's decision under constant review and endeavour to keep all customers, participants, staff and dependent businesses informed as the situation progresses."
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