5. Non-underlying items

	2022 £000	2021 £000
Operating costs	5,424	2,795
Finance expense	674	429
Non-underlying items before tax	6,098	3,224
Tax on non-underlying items	604	(771)
Non-underlying items after tax	6,702	2,453

Non-underlying items before tax consist of:	2022 £000	2021 £000
Amortisation of acquired intangible assets – Harry Peers/DAM Structures	5,191	2,842
Acquisition-related expenses – DAM Structures	–	689
Contingent consideration movements – Harry Peers	–	(736)
Other exceptional costs	233	–
Unwinding of discount on contingent consideration – DAM Structures/Harry Peers	674	429
Non-underlying items before tax	6,098	3,224

Amortisation of acquired intangible assets represents the amortisation of customer relationships, order books and brand name, which were identified on the acquisition of Harry Peers and DAM Structures.

Acquisition-related expenses in the prior year of £689,000, represent non-recurring legal and consultancy fees associated with the DAM structures acquisition.

The basis for stating results on an underlying basis is set out on Our Year in Review. The board believes that non-underlying items should be separately identified on the face of the income statement to assist in understanding the underlying performance of the Group. Their separate identification results in the calculation of an underlying profit measure, which is the same as that presented and reviewed by management. Accordingly, certain alternative performance measures ('APMs') have been used throughout this annual report to supplement rather than replace the measures provided under IFRS, see note 32.