Several of these pieces are in the form of games. Compositions in the form of games have long been a popular and accessible way of engaging young people in the creation of new music.
This game is from Trevor Wishart's "Sounds Fun" also in the British Music collection:
David Bedford's Balloon Music 1 for any number of players from 2 to 1000 each with 2 balloons, a pin and their voices:
Honeywell by Howard Rees is for three groups of young musicians and is conducted by holding up cards instructing the players which material to play:
Like much contemporary music of the day Honeywell is an "Open form" composition with the exact order of the material left to the performers.
You can find the full exhibiton on the Google Cultural Institute here: http://bit.ly/2oPmzJ4