SHARES in UK Oil & Gas Investments (UKOG) tumbled yesterday after the firm announced it has increased its interest in the Weald Basin, where the so-called Gatwick Gusher is located, through a farm-in agreement with Egdon Resources. UKOG has bought a 20 per cent interest in an onshore licence located to the immediate west of the Horse Hill well. The newly acquired licence contains the Holmwood prospect, which was estimated to contain mean gross prospective resources of 5.6m barrels of oil in a competent persons report published by ERC Equipoise in June 2012. Shares closed trading yesterday down by 8.14 per cent at 1.98p. UKOG chair David Lenigas appeared to blame anxieties over Greece for the share performance, tweeting: “Have you seen what Greece is doing to the whole global market place?”.