Engineering and construction group Costain revealed a decline in annual pre-tax profit after it was hit by increased pension interest charge. However the group cheered investors by recommending a final dividend for the year of 0.55p per share, up 10% from the previous year.Profit before tax fell to £18.1m for the year ended 31 December from £23.1m the year before. Revenue for the year increased to £1.1bn from £996m previously.On an upbeat note, Costain said it was confident about future trading. "We are confident that our position in markets underpinned by strategic capital expenditure, regulatory commitment or essential maintenance requirements will continue to stand us in good stead."