Bankers Draft

The last time I sold a car in the UK to a private individual who was unknown to me, I insisted on being paid with a bankers draft instead of a personal cheque. You cannot be too careful when reasonable amounts of money are involved. When we bought our Italian home we paid the vendor, Notaio and agency all by bankers draft (assegno circolare) from our Italian Bank. We considered it business-like and, at least, good manners. Having recently bought a newer model from an Italian dealer that was unwilling to pay a realistic price for our old car we found a chap, unknown to us, willing to pay a fair price. While I have asked him for a bankers draft he claims that the type of cheque he intends to pay us with, from his Banco Posta account is the same as, & as secure as, an assegno circolare. A bankers draft or assegno circolare is, in fact, a cashiers cheque, signed by a bank employee & guaranteed by the bank. His cheque will apparently have only his signature on it so I am reluctant to accept it. Can anyone with a Banco Posta account throw any light on this? Does Banca Posta issue bankers drafts? If so, what do they call them & where will I find (presumably on-line) an example of one. My Italian is not marvelous yet, were I in Italy at the moment, I might try to extract some information from my own bank or even a Banco Posta. Regretfully, this is not the case & I need a rather quick reply.