How long will it be until the firm soars past the next big milestone – the £20 mark? A 33% jumpFrom its current £15.49 share price to the big £20 mark is a whopping 29% difference. If this unproven technology fails to live up to expectations, then the £20 share price might seem a long way away. On a personal note, I've held the shares since around the £1 mark and have read many accounts of reasons the Rolls-Royce share price has run out of gas. That's no guarantee that the £20 mark is coming soon, but I will be, as they say, letting this particular winner run.