The eyes of the political elite may have been focused on the closed doors of Whitehall, but campaigners for assessment reform were desperately hoping they would switch their attention across the Thames to the South Bank.

As the political pickle thickened following last week’s general election, teaching union the NUT served up lunch in the shadow of the London Eye, on the eve of their industrial action.

Billed as an anti-Sats picnic, it was intended to draw attention to the fact that thousands of schools were dropping the tests this year, thwarting the compilation of league tables.

But as a group of activists and parents shivered in the cold with their placards and anti-Sats t-shirts, it didn’t feel much like Whitehall’s first concern.

Fears that the event was being overshadowed by political events did nothing to quell the fervour of many of the 30 or so participants as they bit into their anti-exams chocolate cake, however.

Alex Kenney, the NUT’s executive member for inner London, said: “The boycott is taking place in a really favourable situation, it’s going to create confusion and chaos about the reliability of tests. The political situation may create opportunities for the anti-Sats lobby to gain concessions.”

Former infant teacher and children’s author Alan Gibbons said the boycott would “force the politicians to engage in the idea that there’s an alternative, and sit down and discuss those alternatives”.

Christine Blower, general secretary of the NUT, told the picnickers: “We are here because we think that a few short tests to sum up the whole of a primary school experiences is just nonsense.”

Parents also backed the action, as stickers bearing the slogans “I will not be Sat on” and “I can’t get no SATisfaction” were handed out.

Ken Muller, from East London, said: “I’m relieved my son won’t be put through a stressful and pressured experience for no good purpose.”