Half year to 30 June
Headline operating profit70.161.7
Amortisation of acquired intangible fixed assets(1.9)(2.3)
Operating profit68.259.4
Net finance charge(1.0)(1.2)
Profit before taxation67.258.2
Profit for the period50.843.6

Group revenue was £368.0m, an increase of 6.4% at actual exchange rates and 8.7% at constant currency. Headline operating profit for the six months increased by 14% to £70.1m (H1 2017: £61.7m), and return on sales increased to 19.0% (H1 2017: 17.8%). Headline operating profit at constant currency increased by 15% to £71.2m. Once again, increases in input costs were more than recovered via price increases and the Group maintained a strong focus on cost control and operational efficiency. Statutory operating profit grew to £68.2m (H1 2017: £59.4m).