The calculation of the basic and diluted earnings per share is based on the following data:

Year ended
31 Dec
2017
£m
Half year to
30 June
2018
£m
Half year to
30 June
2017
£m
Earnings
97.1Earnings for the purpose of basic earnings per share being net profit attributable to equity holders of the parent50.643.5
Number of shares
NumberNumberNumber
190,250,855Weighted average number of ordinary shares for the purposes of basic earnings per share190,453,505190,274,928
Effect of dilutive potential ordinary shares:
Share options
190,250,855Weighted average number of ordinary shares for the purposes of diluted earnings per share190,453,505190,274,928
Earnings per share
PencePencePence
51.0Basic26.622.9
51.0Diluted26.622.9
Headline earnings
£m£m£m
97.1Net profit attributable to equity holders of the parent50.643.5
Add back:
2.9Amortisation of acquired intangible fixed assets (net of tax)1.41.5
Less:
(6.4)Impact of US Tax Cuts and Jobs Act treated as an exceptional item
93.6Headline earnings52.045.0
Headline earnings per share
PencePencePence
49.2Basic27.323.6
49.2Diluted27.323.6