Education suppliers have been told to let schools ‘try before they buy’ so that they do not waste scarce on unnecessary products.

Michelle Thomas, executive headteacher of the New Wave Federation of three primary schools in Hackney, told the 200-strong audience at a British Educational Suppliers Association (Besa) conference that her group looks for products that are simple and reduce workload.

Speaking at this week’s event in London, she said: “Have we made mistakes along the way? 100 per cent. Have we bought data management systems that we should never have bought because we could have pulled it off an Excel spreadsheet? 100 per cent.

“So I think there’s a real need sometimes for a trialling period, and I know companies aren’t fans of that because they are giving away secrets.”

She said that the federation has to be “very competitive” when it makes decisions about investment, telling the suppliers in the room that “we look for things that we can trial”.

She added: “What we are looking for all the time is how we can make sure what we are going to buy and what we invest in is have checked it out first, we have trialled it ourselves, we have trialled it with our teachers.”

School leaders at the Summer Insight Day told companies at the event that they delete hundreds of sales emails from potential suppliers without reading them, while one said he had never bought anything following a cold call.

When asked how suppliers had been successful at selling products to schools, Ms Thomas said that when considering what to buy, “word of mouth is extremely important in primary schools”.

“The majority of my sales are referenced from someone else, 100 per cent. I have seen it in a school, and I have asked that headteacher, and I then I have phoned the company myself.”

She added that social media was also “a huge marketplace for where we see things”.