Their influence, however, upon the policy of the government in the other departments, if less absolute, has nevertheless been very large. This impression one obtains both from published documents, and from private conversations, although the former alone can be cited as evidence. As far back as 1845 we find the Lord Lieutenant speaking of the permanent under-secretary as "the main-spring of your government in Ireland."[181:1] But more important than scattered statements of this kind is the information derived from the testimony taken by parliamentary committees of inquiry. One cannot read, for example, the evidence collected in 1900 by the Committee on Municipal Trading[181:2] without being convinced that not only the efficiency, but also in large measure the current policy, of the Board of Trade depended upon the permanent official at its head, and this is true of every branch of the administration.[181:3] Sir Lyon Playfair gave the reason for it when he said: "The secretary being a very busy man is very apt to take the advice of the clerk who has been looking over all the details and the correspondence before it comes to him."[182:1] A superior, indeed, lacking the time to become thoroughly familiar with the facts, must be to a great extent in the hands of a trusted subordinate who has them all at his fingers' ends. It is the common case of the layman and his confidential expert; and it must be observed in this connection that with exacting parliamentary and other duties, the cabinet ministers cannot devote all their time to the work of their departments. [Sidenote: Theoretical Relation of Political and Permanent Heads.]