It depends on the severity of the 'Gross misconduct', but remember though that companies are not really allowed to give bad references. All they are really allowed to do is confirm you worked there and the dates that you were under their employment.
If a company gives you a bad reference along the lines of "You were caught with your hands in the till", then that company would be in the wrong as it is no longer allowed for those types of references to be issued.
But honesty is the best policy. There was a recruit from Glasgow who I knew who made it to the second week of the training course and was called out of the class room one day and was fired on the spot. He basically had not told easyJet that he had been sacked from one of his previous employers, and that information came to light and he was sacked as a result.
The company does say to you to be honest and be upfront, because if you are honest and upfront they can try to help you and will let you know if your "transgression" is a major problem or not.
