(1) In this section, "farming", "trade", "profession", "office" and "employment" have the same meanings respectively as in the Income Tax Acts, but not so as to apply the provisions of those Acts as to the circumstances in which, on a change in the persons carrying on a trade, a trade is to be regarded as discontinued or as set up and commenced, and "a trade of dealing in or developing land" shall include a business of dealing in or developing land regarded as a trade under those Acts.
(2) This section shall apply with the necessary modifications in relation to -
(a) the discharge of the functions of a public authority,
(b) the occupation of woodlands where the woodlands are managed by the occupier on a commercial basis and with a view to the realisation of profits,
(c) a profession, office or employment,
(d) such of the activities of a body of persons whose activities are carried on otherwise than for profit and are wholly or mainly directed to the protection or promotion of the inter
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