single or double inverted commas

They use single "inverted commas," with double used for quotations within the dialog.

'It was very unpleasant' Roger said, 'Especially when she said to me "Bugger off" in front of all our friends.'

American usage is the opposite, and they are called quotation marks.

"I certainly did not enjoy it" Roger said, "Especially when she said to me 'Take a hike' in front of everyone."

Thanks, Setanta, for the detailed reply.

You're welcome, Miss Tan.