The British financial markets stumbled on Monday due the the uncertainty caused by the Scottish independence referendum coming up on Sept. 18.

A poll released by the Sunday Times showed for the first time that the majority of Scotland will vote in favor of independence.

According to Reuters, the poll prompted concern bordering on panic among Britain’s ruling elite, with Prime Minister David Cameron’s Conservative-led government promising proposals this week to grant Scotland greater autonomy if it stays.

The Sterling fell more than 1 percent, which is its biggest one-day drop in 13 months – to $1.6141, long-dated government bonds tumbled and 3.5 billion pounds was wiped off the market value of six London-listed companies with large exposure to Scotland, reported Reuters.

A poll released by the Sunday Times put the “Yes” to independence campaign at 51 percent against the “No” camp at 49 percent.