Bill Mann has stood down as chairman of the eponymous property-to-finance group to make way for his son.

The Glasgow businessman, who fought a successful campaign against tax authorities about his charitable endeavours, has made the move ahead of his 75th birthday next month, some 38 years after he started the business.

Helped by an avowedly conservative approach to business, the low-profile group has amassed a portfolio of residential and commercial property assets and loans to developers and the like across Scotland.

After recording three successive years of seven-figure profits, the company has shareholder funds in excess of £18m.

Mann confirmed that the company had not been immune from the credit crunch that has played havoc with property markets and the stock markets on which the group invests.

"In the current year, to 31st December 2008, there will not be the usual gains on sale of properties or quoted investments," he said in a statement.

Nevertheless, Mann expects the company to achieve pre-tax profits of around £1m, a figure which he said was "beyond his wildest dreams" when he started the company.

In calendar 2007, the group made pre-tax profits of £1,481,219.

Announcing the results in March, Mann noted that while the second half of 2007 was marked by gathering gloom about the likely consequences of the global credit crunch on property markets, the group had not had to write off any bad debts in the year.

As WM Mann Group had refused to revalue its properties in line with market values during the long property boom in prior periods, the company had not been required to write down the value of any of its assets last year.

However, Mann admitted that the credit crunch had influenced the timing of his decision.

He had planned to stand down when the company broke the £2m profits barrier or when he turned 75, whichever was sooner. "The first target now seems a couple more years off due to the credit crunch."

Besides campaigning on issues ranging from business rates to the future of Dowanhill Tennis Club, Mann has been an active supporter of charity. The company is one-third owned by the WM Mann charitable foundation, which supports mainly arts and education charities.

In 2002 and 2003, WM Mann slashed its charitable donations from an average of more than £300,000 a year to only £64,000, after the Inland Revenue disputed whether such payments were tax deductible.

The tax authority backed down in 2004 after five years of haggling. This saved WM Mann £500,000 in back tax.

In 1999, WM Mann gave up its status as an authorised banking institution after 18 years, blaming "increasing, unnecessary and unreasonable demands of the Financial Services Authority'', Mann has been succeeded by his younger son, Bruce. Aged 39, he is a member of the Scottish Institute of Bankers and a graduate from the University of San Francisco. He has worked with the group for more than 13 years.