My hon. Friend would appear to have in mind evasions of Purchase Tax, and of taxes upon profits. So far as Purchase Tax is concerned, all traders registered for Purchase Tax purposes are required to keep full and true accounts both of their purchases and of their sales of such goods as are chargeable with the tax, so that tax may be duly assessed. Failure to keep proper records involves liability to prosecution: and a number of persons have, in fact, been prosecuted under this provision. So far as the taxation of profits is concerned, I can only say that the taxation authorities may be relied upon to take every possible step to ensure that the true profits of a business are ascertained for purposes of assessment. I may remind my hon. Friend that the law provides for estimated assessments to be made, should the taxpayer's return be considered unsatisfactory, and that, on appeal against such an assessment the Commissioners hearing the appeal can call for such further evidence as they consider necessary.