PARIS: June 15, 2017. The OECD is forecasting a 1.7 percent rise in UK GDP this year and just 1.0 percent in 2018 as uncertainty rises of Britain not reaching a Brexit agreement.

The OECD assumes UK external trade will operate on a "most favored nation" basis from April 2019 as it "faces a long-standing decline in its export market share" with manufacturing and agricultural products exposed to global protectionism.

Despite the depreciation of Sterling since last June, the OECD notes UK exports have been volatile and market shares have not risen. In 2015 the country's exports were valued at £517.4 billion, rising to £526.3 billion in 2016 and expected to reach £536.3 billion in 2017 and £551.3 billion in 2018.

By comparison UK imports were £547.2 billion in 2015 and £562.5 billion in 2016, with a forecast of £583.9 billion this year and £591.5 billion in 2018.

"The major risk for the economy is the uncertainty surrounding the exit process from the European Union," the OECD stated. "Higher uncertainty could hamper domestic and foreign investment more than projected, but swift progress in negotiations and an outcome that retains strong trade linkages with the European Union would lead to better outcomes than projected."

The forecast follows a call to the government by the UK trade organization ADS, representing £31.8 billion in annual revenue from the country's aerospace, defense, security and space sectors, to "refresh its Brexit strategy and reach out to a wider community to build consensus for its negotiating priorities".

ADS says a successful conclusion to Brexit would include access to the single market, membership of the Customs union, remaining within European regulatory regimes and examining the controls on freedom of movement.

Noting the UK political climate has changed following the June 09 election, ADS CEO Paul Everitt said Theresa May's government had a vital opportunity to change its approach, with a greater focus on building consensus and a more constructive tone towards with Europe.

"Last week, the country signaled it wanted a more collaborative approach. No deal is the worst outcome for the UK and Europe. Finding the best agreement will require compromise and pragmatic decisions by the UK and its European partners," he declared.

With the 2017 Paris Air Show starting on June 19, Everitt said the UK's long-term prosperity depends on healthy high value manufacturing sectors. "The government must put further political and financial commitment behind its industrial strategy for aerospace, or risk the UK losing out to overseas competitors," he added.