Wingo - yes, £32m is the current market cap. There are approx 75.2 million shares in issue, so £0.43 times 75.2 million = £32.3m
The 75m shares may increase slightly to handle share options granted to both staff and directors, but it is very unlikely to take the number of shares to much more than about 76m before the 2012-2013 annual report is issued.
The 75 million share represents all the shares in issue - it includes the 36m shares owned by the JW trust, the 10.9m shares owned by IAG, the 4m shares owned by Jim French, and all the other shares available for the general public to buy and sell via a standard stockbroker as they see fit. Thus, the JW trust owns shares worth about £15.5m while IAG own shares worth about £1.7m
Wingo - yes, you're right - there is no magic in the formula.