The UK business of Fidelity International has warned in its latest accounts that Brexit will be “complex and drawn out”, but still targeted further growth as its assets under management rose nearly a fifth.

FIL Holdings (UK) Limited – the holding company for the UK business that trades as Fidelity International – said in accounts published at Companies House for the 12 months ended June 30, 2016 that operating profits had risen from £26.3 million the previous year to £39.1 million.