In a TUPE situation which employer is the "transferee" and which the "transferor"?

The seller of the business is the transferor, while the recipient is the transferee. In outsourcing, a client engaging a contractor will be the transferor and the contractor the transferee. If the contract changes hands, the outgoing contractor will be the transferor and the incoming contractor the transferee. If the client takes the service back in house, the outgoing contractor will be the transferor and the client will be the transferee.