It is a tricky one.
The difficulty is that because you have been given notice that this is not a current address for him, the rules say that you have to take steps to establish his current address. However, once you have to no avail, then you can use the former address as a valid address for service.
"(3) Where a claimant has reason to believe that the address of the defendant referred to in entries 1, 2 or 3 in the table in paragraph (2) is an address at which the defendant no longer resides or carries on business, the claimant must take reasonable steps to ascertain the address of the defendant’s current residence or place of business (‘current address’).
(4) Where, having taken the reasonable steps required by paragraph (3), the claimant –
(a) ascertains the defendant’s current address, the claim form must be served at that address; or
(b) is unable to ascertain the defendant’s current address, the claimant must consider whether there is –
(i) an alternative place where; or
(ii) an alternative method by which,
service may be effected.
(5) If, under paragraph (4)(b), there is such a place where or a method by which service may be effected, the claimant must make an application under rule 6.15.
(6) Where paragraph (3) applies, the claimant may serve on the defendant’s usual or last known address in accordance with the table in paragraph (2) where the claimant –
(a) cannot ascertain the defendant’s current residence or place of business; and
(b) cannot ascertain an alternative place or an alternative method under paragraph (4)(b)."
If it was me, I would issue against the England & Wales address and then let him raise the jurisdictional issue if he wants to and deal with it then, showing that you have taken the "reasonable steps" to establish an alternative address.
Hope this helps.
JH Law Solicitors