Why does Les say the angel of the Lord is Jehovah?
The angel of the Lord is Jehovah because Scripture later speaks of "the angel of the Lord who redeemeth me." Since only one Redeemer exists—God the Son, Jehovah in the Old Testament and Christ in the New—the term "angel of the Lord" or "angel of God" identifies God the Son.
Les explains that whenever the term "the angel of the Lord" appears, it refers to Jehovah. His reason is that at a later point, possibly chapter 46, Scripture uses the phrase "the angel of the Lord who redeemeth me." Since there is only one Redeemer in Scripture, and that Redeemer is God the Son—Jehovah in the Old Testament and Christ in the New—the angel of the Lord, or the angel of God, must be God the Son, the Redeemer. He adds that this should never be lost sight of because it will come up again.