It isn't. Steve Perryman about the Seaborne transfer said it was Saints that wanted it to be undisclosed. Every Saints transfer under Liebherr/Cortese has been done this way.
You can't change numbers mid season.
It is just a training bib, means nothing. Hence why Lambert is wearing number 9 and not his number 7. Barnard imo will be number 17 vacated by Paterson.
He'd be great in this league even though he is a Pompey player of 8 years. I'd be happy if he signed as is exactly the type of player Saints need.
One drawback to signing him is that it is giving money to Pompey.
Because with Barnard joining he is a long way from ever starting for Saints.
If he was included in the deal the transfer fee would come down. Southend wouldn't bother saying it was a separate deal if it wasn't.
According to Southend OS Paterson was a...
So it was NOT a swap deal. Very likely a future package arranged with high % sell on clause as he went for free.