By Daniel Moxon Christian Horner could still play a part in Red Bull’s Formula 1 season launch event next week. The 50-year-old team principal is the subject of an investigation initiated by the Red Bull parent company after an allegation of inappropriate behaviour was made against him by a female colleague. Horner has strongly denied the claim. He met with the external investigator brought in by the energy drinks manufacturer on Friday. The conversation, held at an undisclosed location in London, lasted for several hours and gave Horner his first opportunity to tell his side of the story. But…