If anyone is looking for George WILLISCROFT in the WW1 Service Records (WO 363), it may be worth searching under SOPER, G A R.

There is a letter from the OC, 13th Essex Regt clarifying how to record the information (He was instructed to insert "alias George Williscroft" after the name Soper - which to me is the wrong way round!).
Sorry, no Reg No.

Alterations were also to be made to another soldier's record, which is why it is filed under Scott.

Anc****y, SCO, pages 51393 & 51394