shop means any premises where there is carried on a trade or business consisting wholly or mainly of the sale of goods (see Schedule 1, paragraph 1 to the 1994 Act)
	a large shop is a shop which has a relevant floor area exceeding 280 square metres (see Schedule 1, paragraph 1 to the 1994 Act)
	relevant floor area in relation to a shop means the internal floor area of so much of the shop as consists of or is comprised in a building, but excluding any part of the shop, which throughout the [period of seven days ending with the Christmas Day in question], is used neither for the serving of customers in connection with the sale of goods nor for the display of goods (see Schedule 1, paragraph 1 to the 1994 Act)
The words in square brackets above are inserted into the definition in the 1994 Act (in place of a reference to Sunday) by section 1(5) of this Act insofar as the definition applies to the meaning of "large shop" in this Act.
Glossary of Terms Used in the Sunday Trading Act 1994