6. Earnings per share

2007/08 2006/07 2005/06
Net income ($ million) 219.8 252.7 238.0
Basic weighted average number of shares in issue (million) 1,703.8 1,727.6 1,736.6
Dilutive effect of share options (million) 17.6 37.5 3.3
Diluted weighted average number of shares in issue (million) 1,721.4 1,765.1 1,739.9
Earnings per share – basic 12.9c 14.6c 13.7c
Earnings per share – diluted 12.8c 14.3c 13.7c
Earnings per ADS – basic 129.0c 146.3c 137.0c
Earnings per ADS – diluted 127.7c 143.2c 136.8c

The basic weighted average number of shares excludes shares held by the Employee Stock Ownership Trust ("ESOT") as such shares are not considered outstanding and do not qualify for dividends. The effect of this is to reduce the average number of shares in 2007/08 by 2,146,735 (2006/07: 3,253,096; 2005/06: 3,745,265). The calculation of fully diluted EPS for the 2007/08 excludes options to purchase 33,793,507 shares (2006/07: 17,846,848 share options; 2005/06: 26,826,235 share options) on the basis that their effect on EPS was antidilutive.

Each ADS represents ten ordinary shares.