The original dish was brought to Lazio from Umbria by coal men (carbonari), who ventured to sell charcoal to the Romans.
After spending 3 years both working and living in northern Italy, Emilia Romagna (Ferrara), I can confirm that this is a genuine recipe and not something that has been adapted for the British palate; there is no cream in use here.
Even the use of tagliatelle is permissible to the Nonnas.
Feel free to switch the guanciale out for pancetta but do not compromise on the cheese, use Pecorino Romano, accept no substitute.
Download the .pdf from this link: Tagliatelle Carbonara