Simon Thompson, a Non-Executive Director of FTSE 100 resources company Tullow Oil, has added 8,419 shares to his stake in the firm following its announcement of a recent discovery.The discovery saw the company source further oil in the first exploration well at one of its Kenyan projects, increasing its potential 'significantly', the group said on Tuesday. Thompson handed over a total of around £99,500 for the shares, which were purchased in two transactions of 3,431 at 1449.4p and 4,988 at 1495.8p, respectively. The purchases increased his total holding to 10,166 shares. The Ngamia-1 well, located in the Turkana Country of Kenya Block 10BB, is the oil company's first prospect to be tested as part of the project in Kenya and Ehtiopia. Following an announcement on March 26th that said that the well had encountered in excess of 20m of net oil pay, the well was then deepened from 1,041m to 1,515m and a total pay count greater than 100m has now been discovered. Top Director BuysSinclair Is Pharma (SPH) Director name: Mr Jean-Charles TschudinAmount purchased: 131,300 @ 26.46p Value: £34,742JPMorgan Russian Securities (JRS) Director name: Mr Alex EastonAmount purchased: 5,000 @ 508.50p Value: £25,425Matra Petroleum (MTA) Director name: Mr James William (Bill) GuestAmount purchased: 555,555 @ 2.66p Value: £14,778Ashmore Global Opportunities Ltd GBP Shares (AGOL) Director name: Mr Christopher LeggeAmount purchased: 2,500 @ 590.00p Value: £14,750El Oro Ltd (ELX) Director name: Mr Robert E. WadeAmount purchased: 10,000 @ 114.50p Value: £11,450Telecity Group (TCY) Director name: Mr Michael TobinAmount purchased: 1,500 @ 756.67p Value: £11,350NR