2017 | 2016 | 2015 | ||||||||||
$M | $M | $M | ||||||||||
Research and development expenditure charged to the consolidated income statement | 6.9 | 5.5 | 5.8 | |||||||||
Development capital expenditure included within non-current assets (Note 12) | 0.9 | 2.1 | 2.5 | |||||||||
Total research and development expenditure | 7.8 | 7.6 | 8.3 | |||||||||
Less development expenditure capitalized within non-current assets | (0.9 | ) | (2.1 | ) | (2.5 | ) | ||||||
Net research and development | 6.9 | 5.5 | 5.8 | |||||||||
Depreciation of property, plant and equipment (Note 11) | 16.7 | 16.7 | 16.6 | |||||||||
Amortization of intangible assets (Note 12) | 2.3 | 1.7 | 2.2 | |||||||||
Loss on disposal of property, plant and equipment | 0.1 | 0.2 | — | |||||||||
Operating lease expense (Note 26) | 5.1 | 4.8 | 5.6 | |||||||||
Restructuring and other expense (Note 5) | 21.6 | — | 2.2 | — | 22.4 | |||||||
Net foreign exchange gains | — | — | (0.7 | ) | (0.6 | ) | ||||||
Staff costs (Note 6) | 121.3 | 111.7 | 119.3 | |||||||||
Cost of inventories recognized as expense | 282.9 | 287.3 | 316.2 | |||||||||