(ShareCast News) - Self-storage provider Big Yellow Group reported an increase in revenue in the first quarter of the year, driven by the acquisition of its regional portfolio joint venture.The FTSE 250 group said its total revenue in the three months to the end of June was £24.1m, a 28% increase year-on-year, boosted by the acquisition, completed in December, of the remaining 67% of the Big Yellow Partnership Ltd, its regional joint venture.Like-for-like revenue, which does not include the recently-acquired regional stores, also increased, climbing 10% compared to the corresponding period a year ago to £20.7m.The group said its closing occupancy rate at the end of June was 75.5%, a 4.3% hike year-on-year, while on a like-for-like basis, its closing occupancy rose 5.1% to 76.3%.However, the company's closing rent per square foot declined 4% to £25.4m in the period."Overall, our first quarter has seen a continuation in the positive trading momentum we achieved last year," said chief executive James Gibson."As previously indicated the uncertainty in the lead up to the General Election did result in softer trading in the first half of the quarter."However, following the conclusive outcome, we saw an improvement in demand, with a return to more normal trading, and a strong performance in the second half of the quarter."Big Yellow shares were up 1.41% to 682.50p at 08:24 on Thursday.