The live blog below will be updated throughout the two hour race for the Avon Tyres British GT Championship which starts at 2:05pm UK time.
16:13PHOTO FINISH: Mardenborough beats Jonny Adam to the line by just 0.022 seconds to applause from the media centre.
16:10two minutes to go – Jonny Adam takes second at Paddock Hill Bend!
16:05Six minutes to go and the top three are covered by just three seconds. THREE SECONDS!
16:01ten minutes remaining. Mardenborough leads by 1.8 seconds over Oliver Bryant, but Jonny Adam is homing in on both of them, just 5 seconds down on Bryant’s BMW.
15:59Jody Fannin – having taken the GT4 lead is now 14 seconds to the good over James May.
15:58Bryant turns a slow lap, and the lead is back out to 2.4 seconds but Jonny Adam is now just 6.8 seconds away from taking second place.
15:55Mardenborough’s lead is back under two seconds, Bryant taking another three-tenths out of the gap which stands at 1.9 seconds with 15 minutes remaining . Adam is just 11 seconds off the lead, but is still a second a lap faster.
15:51Fannin takes the lead for Team WFR, passing James May at Druids as the GT4 and GT3 lead battles overlap with Bryant lapping them both.
15:48Bryant takes another half second off the lead, but the fastest man on track is Jonny Adam in the BeechdeanAston Martin, who’s more than a second quicker the Bryant in third place.
15:46The GT4 lead is back down – Fannin just seven-tenths behind James May now, and Bryant is closing in Mardenborough for the overall lead again – the gap down to 4.7 seconds.
15:44So now it’s Adam, Murrells and Nicolas Armindo in the fight for third place.
15:41Harvey makes an unscheduled pit call to replace a left rear tyre. New slick going on as it’s not raining (at least in the pits).
15:40Tim Harvey, Jonny Adam and George Murrells are split by just six tenths in the fight for third.
15:37It’s raining again and Oliver Bryant is falling away from the leader – the lead back to five seconds now.
15:36Tim Harvey is now third overall, and in GT4 Jody Fannin’s march to the class lead in GT4 is faltering.
15:31Bryant has Mardenborough’s lead to just 1.7 seconds, with 40 minutes of racing still to go. Stephen Jelleyruns third, but he too will have to serve a one second stop-go penalty.
15:30Third place Matt Bell gets a 1 second stop/go penalty – presumably for a pit stop too short when he took over from Charles Bateman.
15:25Bryant is gaining on Mardenborogh, but both are pulling away from Matt Bell in third for United Autosports
15:22James May (not that one) returns the APO car to the track but with just 15 seconds advantage in GT4 over the rapid Jody Fannin in the Team WFR Ginetta
15:19Osborne finally pits from the lead with 53 laps remaining. Mardenborough takes the lead back fof RJN, chased by Oliver Bryant in the Ecurie Ecosse BMW Z4.
15:15Alex Osborne leads overall in the GT4 APO Sport Ginetta G50. Both he and Mike Ticehurst in the Mazda are yet to stop.
15:13Buncombe pits after 34 laps for Nissan GT Academy winner Jann Mardenborough to take the controls of the lead Nissan.
15:11Lap 33: Luke Hines brings the Optimum Motorsport Ginetta G55 in from the lead, leaving Buncombe alone out front as the race crosses the half way point.
15:09Lap 22. David Jones brings the Preci-Spark Mercedes SLS into the pits from third. The safety cars have really helped them after taking a drive-thru penalty early on.
15:03pit window opens and David Ashburn leads the first pit callers, Nicolas Armindo takiing over the #31 Trakspeed Porsche. Alasdair McCaig, Jon Minshaw and Steve Parish also pit.
15:00The Hetherington Nissan returns to the pits with massive front damage as the safety car comes in just a minute ahead of the pit window opening.
14:50Alex Osborne leads GT4 for APO Sport after spinning lap one, ahead of Warren Hughes in the Team WFRGinetta G50.
14:49Buncombe leads Hines, Charles Bateman, David Ashburn (Trackspeed), Alasdair McCaig (Ecurie Ecosse)and Andrew Howard.
14:48We’ve got another Safety car as we lose the JMH Nissan of Benji Hetherington from fourth place somewhere on the GP loop.
14:43Debris on circuit the reason for the quick safety car period. we’ll be green this lap with 17 minutes still remaining until the pit window opens.
14:41Half an hour in and the Safety car is out. No news on why yet.
14:37Duncan Cameron explains that Hector Lester spun the Rosso Verde car infront of him, leaving him nowhere to go. Cameron in the MTECH car is out of the race.
14:35Buncombe slips wide – possibly on fluid from the damaged Ferrari of Duncan Cameron. Buncombe continues in the lead but Daniele Perfetti is off at Druids after contact with David Jones in the Mercedes SLS
14:32The Ginetta G55s are the fastest cars on track – Hines sets fastest lap as he starts to break down Bincombe’s lead. Riki Christodoulou also on the pace but down in ninth.
14:28Steve Parish spins at Surtees, dropping the pole sitting Porsche out of third place.
14:28After 15 minutes and 8 laps Buncombe now leads Luke Hines by nearly 7 seconds, with the two MotorbasePorsches
14:26Luke Hines is up third by Daniele Perfetti on the GP loop, now pushing Parish for second place.
14:23L6 Duncan Cameron spins the MTECH Ferrari 458 out of fifth place down to 19th at Paddock Hill Bend.
14:21Lap four – Buncombe, Parish, Perfetti, Luke Hines, Duncan Cameron, David Ashburn, Jon Minshaw
14:20Mike Ticehurst is leading GT in the Jota Mazda MX5 after three laps.
14:17Lap two and Buncombe leads, passing Steve Parish at Clark Curve to push the Porsche man to second place with Daniele Perfetti third.
14:16Alex Buncombe is up to fourth in a single lap after starting ninth in the RJN Motorsport Nissan GT-R.
14:15Race underway. John Dhillon spins at Paddock Hill in the Scuderia Vittoria Ferrari, with GT4 pole man Alex Osborne spinning behind him. Steve Parish in the #10 Motorbase Porsche leads out onto the GT loop for the first time.
14:13Yep, it’s raining.
14:12Umbrellas around the track show it might be raining again.
14:11Race director not happy with the grid formation, so we have a second lap behind the Juke R safety car, but it does count in the two hours.
14:08Andrew Howard‘s Beechdean Aston Martin is refusing to fire up on the grid. Team run back to get the#007 under power and the pack begin the green flag lap.
14:06Team personnel are clearing the grid ahead of the start of the race. The track is damp, but the rain has stopped and everyone is starting the race on slick Avon tyres.