Doubt over the outcome of Thursday’s unpredictable U.K. general election is dampening property price rises in prime outer London markets, which increased by just 0.3% in April from the month before. Knight Frank’s Prime Outer London Index for April recorded a slowdown in annual growth to 4.5% from 12.1% from the previous year. The market for properties worth £2 million or more has been particularly affected over fears of the so-called mansion tax that may be introduced should a Labour government come to power. The proposed tax would apply to homes worth £2 million or more. Meanwhile, prices in prime central London have remained broadly flat in recent months and annual growth dipped to 2.8% in April, the lowest rate since November 2009. This followed an “exceptionally strong” run of growth, which, says Tom Bill, head of London residential research at Knight Frank, “saw prime central London property cement its global reputation as a safe investment.” With political uncertainty replacing economic uncertainty, Knight Frank now forecasts zero growth in prime central London in 2015, and 3% growth in prime outer London. This is expected to pick up to 4.5% and 5.5% respectively in 2016, once the new government has had the chance to bed in. Many vendors are waiting for the result of the election and its impact on house prices before putting their homes on the market. Others have moderated asking prices, which has resulted in a small rise in demand for properties worth more than £2 million since the beginning of the year, particularly in South-West London. Bill said: “The election has created a mood of uncertainty across all price brackets. But there is evidence of pent-up demand in the sales market which means vendors are likely to act once the election is over. There are a number of properties that will go on the market on Monday 11 May, irrespective of the outcome, which suggests a pick up in transaction levels.”