SONS and fathers, sisters, brothers, even husbands and wives have been known to rally cars against each other, and in some cases with each other in the same vehicle - although the final potentially fraught combination is, not surprisingly, the most rare.

However, Castle Douglas's Barbara and Jock Armstrong have arguably cornered the market as rallying's first sister-and-brother duo, whose rivalry and mutual support could be at risk if the male sibling cannot raise sufficient finance to continue competing.

In an ironic reversal of fortunes Jock, 26, whose career appeared to be in the ascendant, is threatened with the unappealing role of bystander while Barbara, after a fragmented four years on the fringes, becomes a professional works rally driver at the age of 31.

While Jock launches a search for between #30,000 and #40,000 in commercial backing, Barbara will drive for the Seat team in the British Mobil/Top Gear championship at the wheel of a potent 260-horsepower Ibiza ``kit car''.

Kit car regulations allow manufacturers greater leeway in terms of modifying the cars for higher performance and bolting on aerodynamic aids.

The other lurid green (officially designated Kiwi yellow) Spanish car will be handled by Finn Harri Rovanpera, winner of last year's Scottish International Rally, and the debutante UK team is aiming to emulate Seat's success as last year's Formula 2 rallying world champions.

While involving a woman rally driver generates inevitable publicity value, Seat deny Barbara's inclusion has anything to do with tokenism. To support the company's selection, Barbara came within an ace of beating former British champion Alister McRae at the recent Autosport show Birmingham NEC arena challenge in her first run with the Ibiza.

Jock is ``really chuffed'' for his sister, who has spent the past five years exiled in Daventry earning a living as an instructor with the Silverstone Performance Driving Centre.

Her job description takes in teaching a wide variety of driving disciplines, from advanced defensive techniques to racing and rallying. Under-employed competition drives frequently resort to manufacturers' track days with the aim of teaching car company customers the differences between thinking you can drive rapidly and safely and the reality.

Blunt criticism of the driving approach of Seat's marketing manager, Gary Savage, who established the company's sessions last Spring, proved an unconventional way of gaining rallying patronage. Barbara also did not grill her captive student about sponsorship, or demand a drive. Three events driving clubman specification Ibizas led to an outing on the RAC Rally and in turn to the coveted Seat contract.

Meanwhile, a test session in Portugal with works world-series drivers Erwin Weber of Germany and Rovanpera beckons. The unstated aspiration would be to graduate from the hard school of UK rallying to the world stage, in the wheel tracks of 1990 world women's champion Louise Aitken-Walker.

Being offered the current challenge was, according to Barbara: ``Like getting all my Christmases at once.'' Her target is to win at least one round of the F2 championship, preferably on home soil at the Dumfries-based Scottish event. The formidable opposition will include countrymen Robbie Head in Renault's Megane Maxi, Alister McRae's Volkswagen GTi, and hopefully brother Jock.

Barbara has been involved in rallying since 1983, first as a navigator for local Galloway crews before a local company, Dalplant, sank #15,000 in cash so she could rally a Talbot Sunbeam Ti. Between 1989 and 1992 her name appeared on the entry lists of the Peugeot Challenge, and despite consistently competitive performances the 309 GTi she campaigned was no match for the lighter, more nimble 205s. Fifth overall was the best result.

During 1995 and 1996, Jock was a beneficiary of Shell's rallying scholarship scheme. Seventh and thirteenth overall in the British series did not reflect his performances on board a Nissan sunny, which he bought from Shell at the end of last season.

Armstrong is selling on the Sunny and hopes to make up the difference from sponsorship. His potential options include a production (Group N) Subaru Impreza Turbo or access to a VW Golf GTi run by SBG Motorsport, Alister McRae's team.

Jock Armstrong burst on to the scene in 1993 by winning the UK Colway Tyres budget championship in a 1300cc Vauxhall Nova, against more powerful cars. He was top rookie in the 1994 Peugeot Challenge and graduated to the two-year Shell scholarship driving Nissans.

PR and selling the sport are central to Shell's scheme and Jock believes the logistical format of the British series offers an ideal package for a southern Scottish backer. The Scottish Rally's Border location is complemented by the opening Pirelli-backed Cumbria round in Carlisle, while the Ulster and Isle of Man events also come within a handy geographical radius.

Although he does not pour money into the rally fighting funds of Barbara and Jock, father Jock, who runs a thriving construction business, does act as occasional benefactor.

This has extended to the novel form of fatherly twenty-first birthday gifts. A taxi business in the case of Barbara and a building firm when Jock came of age. Seat is paying her current driving fare while brother Jock is determined to progress beyond the existing foundations.