Nothing in section 31 requires the doing of anything in relation to a letter or other postal packet—
whose weight exceeds 20 kilograms, or
whose dimensions fall outside the minimum and maximum dimensions laid down in the Convention and the Agreement concerning Postal Parcels adopted by the Universal Postal Union.
The requirements in section 31 in respect of the delivery or collection of letters or other postal packets (requirements 1 and 2)—
do not need to be met on any day which is (in the part of the United Kingdom concerned) a public holiday, and
do not need to be met in such geographical conditions or other circumstances as OFCOM consider to be exceptional.
Nothing in section 31 is to be read—
as requiring a service to continue without interruption, suspension or restriction in an emergency, or
as preventing individual agreements as to prices from being concluded with customers.