European Le Mans Series GT class front-runner James Walker will make his prototype debut with the Delta-ADR squad in the opening round of the World Endurance Championship at Silverstone.
The Briton, who won GTE Pro three times in the ELMS with the JMW Ferrari team in 2011-12, will drive one of the Delta-ADR's two LMP2 class ORECA-Nissan 03s alongside Antonio Pizzonia and Tor Graves.
"This came out of the blue, but I'm over the moon to get the chance in a prototype, especially at Silverstone, said Walker, 29. "I haven't driven anything with a lot of downforce since doing Superleague in 2010, so I'm looking forward to the chance."
He explained that the deal could be extended to more races.
"The chance is there, especially if I do well," he said. "This has been a last-minute deal, but to stay on in the car would require me to start working to put the budget together."
Walker, who raced one of Fortec's new Mercedes-Benz SLS AMGs at the opening round of the British GT Championship at Oulton Park last weekend, revealed that he was expecting a "season of one-offs" in 2013.
"That's not what you plan for," he said, "but it will give me the chance to show what I can do in a range of machinery."
Walker is exploring options in the Blancpain Endurance Series, the GTC class of the American Le Mans Series and the Porsche Carrera Cup Asia for the coming season. He will not continue in the ELMS with the JMW Ferrari squad, which is shortly to announce its drivers for 2013.
The lineup for the ORECA that Delta-ADR will run under its own name in the WEC remains fluid. Pizzonia is also doing Silverstone on a one-off basis and only Graves is confirmed for the full season.
Marussia Formula 1 reserve driver Rodolfo Gonzalez is a possibility for number of WEC races that do not clash with grands prix. The Venezuelan was due to try out for Delta-ADR at last week's official WEC test at Paul Ricard, but failed to get any laps after minor incidents for both cars.
The lineup in the ORECA that Delta-ADR will run under the G-Drive Racing banner is fixed for the full season, with John Martin and Mike Conway joining Roman Rusinov.