Ah well, POGS! Sorry, I'm not in clever dick mode! ;-( However, I might have found your answer from the Information Commissioner's Office.
"Sensitive personal data means personal data consisting of information as to -
(a) the racial or ethnic origin of the data subject,
(b) his political opinions,
(c ) his religious beliefs or other beliefs of a similar nature,
(d) whether he is a member of a trade union (within the meaning of the Trade Union and Labour Relations (Consolidation) Act 1992),
(e) his physical or mental health or condition,
(f) his sexual life,
(g) the commission or alleged commission by him of any offence, or
(h) any proceedings for any offence committed or alleged to have been committed by him, the disposal of such proceedings or the sentence of any court in such proceedings."
In other words, financial details aren't covered by the Act.
I suspect that your club is being over-cautious and has misinterpreted the Act, in the same way that many 'elf and safety rules are actually over-zealous interpretations of the law.