Notwithstanding anything in the preceding provisions of this Schedule, if it appears that the transaction by which an asset was acquired by the company had as its sole or main purpose the reduction of the amount of the company's chargeable profits or, as the case may be, corresponding United Kingdom tax for any accounting period (by virtue of the assumption of a relevant allowance in respect of that asset), it shall be assumed that no relevant allowance is available to the company in respect of expenditure incurred on the acquisition of that asset.