UK and European stocks opened on a firm note amid signs of easing Middle East tensions and growing expectations of a Fed rate cut in September.
The U.S. dollar extended its early weakness against other major currencies in the Asian session, as investors awaited revisions to U.S. payrolls data later in the day.
Oil futures settled lower, although the downside was far less pronounced compared to the previous sessions.
Gold prices were trading below record high levels after a rally fuelled by Western fund inflows and U.S. rate-cut optimism.
Costain has announced a £10m share buyback programme as it reported higher profits for the first half on the back of improved margins and a better product mix.
This was driven mainly by an "improved performance in Transportation resulting from a better margin mix derived from newer contracts and increased volumes, and margin in Natural Resources, which has a greater mix of consultancy services", the company explained.
"As a result of our confidence in our long-term prospects, and our strong cash position, we have today announced a £10m share buyback which will commence with immediate effect."