The following is from NHBC Standards Chapter 8.
c) airing cupboards
Airing cupboards are required in homes which do not have central, or whole home, heating. In other cases they are optional.
Where provided, airing cupboards should have:
*
not less than 0.5m² of easily reached shelving suitable for the airing of clothes
*
a vertical space between shelves of not less than 300mm
*
a suitable heat source, such as a hot water cylinder or an equivalent.
Care is necessary when designing airing cupboards. To be accessible, the shelving should be placed not higher than 1.5m.
The airing area should be separated from other storage.
If you have central heating and it did not specifically say 'airing cupboard' on the plans then shelving is not a requirement.
However it is worth putting it down as a snag. Play innocent and insist that it is obviously an airing cupboard!