In 2003, Cally curated SURPRISE, SURPRISE!, an exhibition of contemporary art by fifteen artists chosen specially for the pleasure and interest it would give to primary school children.

The exhibition toured six primary schools in High Wycombe (Hamilton Primary School, Ash Hill Primary School, Beechview Middle School, Disraeli Primary School, Castlefield Primary School, and High Wycombe Church of England Primary School) and Wycombe Museum.

The artists involved were Nick Bodimeade, Tineke Bruijnzeels, George Buckland, Sally Bulteel, Sylie C, Jean Davey-Winter, Kris Emmerson, Linda Francis, Alan Franklin, Hatch Jenkins, Yu-lan Liu, Boo Ritson, Lucy Soutter, Cally Trench and Imogen Welch.

Thea Jourdan: Review of Surprise, Surprise!

Cally Trench showed four of her early mystery boxes in SURPRISE, SURPRISE!: Black Boxes.

Children, teachers and visitors were also invited to reach into Cally Trench's What is Art? Lucky Dip, and to keep what they found as a souvenir.