Two brothers from Blackburn whose parents came to Britain “with nothing” stand to gain a £5bn fortune by floating their petrol station empire.
The company currently exists and they own half of it. Therefore they currently have a fortune.
True, it might become a little larger, as significant stakes in listed companies tend to be worth more than similar stakes in privately held ones.
But the “gain a fortune” part is simply wrong. They have a fortune. The listing isn’t what creates it at all.