Over thirty cars are expected to line-up for the penultimate round of the 2012 Avon Tyres British GT Championship at Silverstone this weekend. A healthy mix of GT3, GT4 and GTCcars will contest the jewel-in-the-crown three-hour event that gets underway at 11:40am BST on Sunday.

With all to play for in the GT3 championship, just two points separate five drivers at the sharp-end of the standings, which is currently headed by 2010 Champion, David Ashburn (Trackspeed Porsche). This weekend Ashburn will again partner with the rapid, Phil Keen as he seeks to extend his half-point lead over MTECHs Duncan Cameron and Matt Griffin (Ferrari).

Silverstones fast flowing nature should suit a number of challengers, not least RJN Motorsports Nissan GT-R NISMO GT3, driven by Alex Buncombe and Jann Mardenborough. The pair are two points shy of Ashburn, and Mardenborough especially will be looking for a victory to help him celebrate his 21st birthday in style on Sunday.

Behind the current leading fivesome are a number of drivers who could join the title race should they have a good points haul this weekend. With points and a half on offer for races over the 60-minute sprint race format, all is very much to play for this weekend.

Alasdair McCaig (Ecurie Ecosse), Michael Caine and Daniele Perfetti (Motorbase), Jonny Adam and Andrew Howard (Beechdean) and the Championships only double winners this year, Steve Tandy and Joe Osborne (Trackspeed) are still all in contention shouldresults go their way.

A wealth of new faces will join or re-join the grid this weekend too. Aston Martin will be represented by two examples of the V12 Vantage GT3 car this weekend. Joining Beechdean Motorsport will be Cyber Racing, a team comprising of the driving talents of GT regular, Phil Dryburgh and Aston Martin Racing MD, John Gaw.

Nigel Mustill brings his Wessex Vehicles prepared Audi R8 LMS to join the ranks of British GT for the first time too; the experienced club-racer will be partnered by a man who knows a thing or two about sports cars and the Silverstone track, the 2011 Group C Championship victor and multiple Le Mans entrant, Bob Berridge.

Another welcome addition to the Silverstone grid is the FF Corse-prepared Ferrari 430 GT3 of Austrian duo Gerard Grohmann and Thomas Kemenater, racing in the UKs top GT series for the first time ever.

As announced last week, reigning champions Glynn and Jim Geddie will take part for the first time in 2012 with their Apex Motorsport McLaren MP4-12c, and re-joining the series after a six-year break is Team LNT. Ginetta Boss Lawrence Tomlinson will lead driving efforts for LNT alongside Ginetta factory driver, Mike Simpson in aGinetta G55 GT3 as the firm seek to further the development of the new British sports car.

Returning to join the increasing ranks of GT3 are 2009 champions, Godfrey and David Jones in their exquisite Mercedes SLS AMG. After missing the Snetterton round for personal reasons, the pair will look to assert themselves amongst the series frontrunners once more.

Experienced British driver, Marco Attard will again join the series in the exciting Rhinos Leipert Motorsport Lamborghini LP600+, with the teams owner, Marcel Leipert returning alongside him for the first time since Mays event at the Nrburgring.

While it is all to play for in GT3 this weekend, the GT4 class honours could be decided come Sunday afternoon. Having led from the off, Team WFRs Jody Fannin and Warren Hughes look set to take the 2012 title if they carry on their sensational 2012 form. The pair can win the class even if they finish fourth and nearest rival, Zoe Wenham (Century Motorsport) wins the 120-minute race.

Wenhams Century team-mate Dom Evans lies third in the GT4 class after missing the opening round at Oulton Park, but has incentive to push hard and support his team-mate as his position in the championship is far from safe.

APO Sports Alex Osborne and James May are closing in on Evans and will be looking for a victory at their local circuit. The pair are confident theyve overcome the reliability issues that dogged them at Snetterton and will be looking to be the first Ginetta G50 to cross the line on Sunday.

As with GT3, GT4 has a number of new faces who will seek to take overall honours in the class. Lotus Sport UK is back with a bang, a two-car entry from the Norfolk-based team showing their intentions. Dutch duo Melroy Heemskerk and Roger Hodenius have driven the Evora in Holland recently, and will be quick from the off. British driver, Chris Holmes makes his first 2012 appearance this weekend too, his driving partner is TBC in the #48 Evora.

Benjamin Franassovici, Championship Manager, British GTSilverstone is a special event for us as it is our only three-hour race. Coming at such a key time of the season a lot of title hopes can either gain momentum or disappear. The additions to the grid add depth to what has been an already strong season, and Im looking forward to some exciting racingit will be great to see so many cars on the Silverstone circuit. With the possibility of the GT4 titlebeing decided this weekend, we have two strong champions elect in the form of Warren and Jody and Zoe has been a real credit to the championship in her first year of GT racing. Overall, GT4 has been a real success this year, and something we intend to build on next year as the championship grows. Hopefully the weather will be kind to us, were due a dry race at some point this year!

Championship points after round five:GT31. David Ashburn Trackspeed 104.5pts2. Duncan Cameron/Matt Griffin MTECH 104pts3. Jann Mardenborough/Alex Buncombe RJN Motorsport 102.5pts4. Alasdair McCaig Ecurie Ecosse 85.5pts5. Daniele Perfetti/Michael Caine Motorbase 81pts6. Steve Tandy/Joe Osborne Trackspeed 78.5pts7. Andrew Howard/Jonny Adam Beechdean 75pts

GT41. Jody Fannin/Warren Hughes Team WFR 187pts2. Zoe Wenham Century Motorsport 127.5pts3. Dominic Evans Century Motorsport 100.5pts4. James May/Alex Osborne APOSport 82pts5. Sailesh Bolisetti/Phil Glew Lotus Sport UK 71pts

Full points: http://bit.ly/Mi5AsA

Silverstone Timetable:Sat 8 Sept: 9:00-10:00 FP1; 11:50-12:50 FP2; 16:35-17:20 QualifyingSun 9 Sept: 9:00-9:10 Warm-up; 11:40-14:40 Race