“105. We are of the view that the question whether a taxpayer has engaged in negligent conduct is a question of fact in each case. We should take the words of the statute as we find them and not try to articulate principles which could restrict the application of the statutory words. However, we accept that negligent conduct amounts to more than just being wrong, or taking a different view from the Revenue. We also accept that a taxpayer who takes proper and appropriate professional advice with a view to ensuring that his tax return is correct, and acts in accordance with that advice (if it is not obviously wrong), would not have engaged in negligent conduct.”