Daejan Holdings reported a jump in pre-tax profit in the first half as the British-based property business saw gross rental income grow.Pre-tax profit rose to £134m in the half year to 30 September from £76m a year earlier, after accounting for a net valuation gain on investment properties of £107.9m and fair value losses on financial instruments of £0.6m.Gross rental income rose 21.6% to £10.6m, supported by the one-off impact of the £7.9m settlement of a contested rent review on the Strand Palace Hotel.The half year results also were boosted by the new letting of Africa House at the bottom of London's Kingsway.The group said the rental benefit the resolution of the rent review and the new letting of Africa House will continue to accrue in future years but increases in the capital values of the properties were "likely to be more modest, in line with the market as a whole".The company added that the US economy continues to grow and the UK outlook continues to show improvement, largely confined to London."Uncertainty created by the upcoming general election and issues such as the UK's future relationship with the EU combine to make the immediate future particularly hard to predict with any certainty," the group said."Nevertheless, we believe that our tried and tested strategy, based on the prudent long term pursuit of growth in asset values, will enable us to make continued progress in challenging times."