A Floating Pier (5,4)

[paynekjk]

Children’s society quiz

[cashier]

What's the theme please?

[Calibax]

Swiss Roll

[cashier]

Water dock?

[Calibax]

Swiss roll n a thin cake of sponge rolled up with jam, cream, etc; a flexible floating pier. (Chambers)

[paynekjk]

Thank you calibax, but which chambers, and how did you get there?

[Calibax]

In my copy of Chambers Dictionary. I couldn't find an online dictionary reference but it's mentioned here under "Trials"
https://en.wikipedia.org/wiki/Mulberry_harbour

[choux]

Calibax is correct, well done.
In Bradford's entry for 'pier(s)' the swiss roll is included.