Where a non-resident person is chargeable to income tax in the name of any branch or agent in respect of any profits or gains arising from the sale of goods or produce manufactured or produced out of the United Kingdom by the non-resident person, the person in whose name the non-resident person is so chargeable may, by notice included in a return of income delivered within six years from the end of the year of assessment for which he is chargeable, elect to be assessed in respect of those profits or gains on the basis of the profits which might reasonably be expected to have been earned by a merchant or, where the goods are retailed by or on behalf of the manufacturer or producer, by a retailer of the goods sold, who had bought from the manufacturer or producer direct.