(5) Any unstamped or insufficiently stamped instrument which has been first executed at any place out of Saint Lucia, shall in relation to stamp duty be deemed to have been first executed on the date of its first receipt in Saint Lucia. However, a power of attorney wholly or partly executed out of Saint Lucia may be stamped, without any penalty, at any time before it is annexed to, or deposited among, the minutes of a notary, or is registered or acted upon.