The question is to be determined having regard to the way an organisation is structured and the employee's contractual duties within it, held the EAT in London Borough of Hillingdon v Gormanley.
Robert Gormanley Limited (RG) was a firm employing three members of the same family. It carried out painting and decorating work for the housing stock operated by the London Borough of Hillingdon. Hillingdon then told RG that it was not going to be given any more work and took the service back in house.
A central question was whether the three employees were assigned to an organised grouping of employees, the principal purpose of which was to carry out the activities concerned on behalf of Hillingdon, the client. The Employment Judge (following the finding of another Employment Judge at a pre-hearing review), held that the employees were assigned to an organised grouping of employees working within RG Limited on behalf of Hillingdon.
However the decision was overturned by the EAT. Neither Employment Judge had failed to make findings of fact relevant to the assignment issue.
The key authority on the definition of assignment remains the CJEU decision in Botzen v Rotterdamsche Droogdok Maatschappij BV  ICR 519. This ruling requires consideration of the contractual duties of employees and their role in the organisational framework of the putative transferor.
In the present case, both Employment Judges had failed to consider the organisational framework within which the employment relationships of the employees took effect. The EAT considered that as the Claimants could be called upon to perform duties other than for Hillingdon under their contracts of employment (for example one of the employees was company secretary), the ruling that the employees were assigned to the Hillingdon contract had to be set aside.