Durham opening batsman Keaton Jennings became the first player to reach 1,000 Specsavers County Championship runs this season .
Durham opening batsman Keaton Jennings could not prevent Middlesex from claiming an innings victory which extends their lead at the top of Division One .
Durham opening batsman Keaton Jennings became the first player to reach 1,000 Specsavers County Championship runs this season but could not prevent Middlesex from claiming an innings victory which extends their lead at the top of Division One .