Walter appears to have arrived in Scotland in about 1136, during the reign of David I, King of Scotland. Following Henry's death in 1135, the Fitz Alans evidently sided with David in his support of the contested English royal claims of Henry's daughter, Matilda. Certainly, both William and Walter witnessed acts of Matilda in 1141. In any event, the date of Walter's introduction into Scotland may be marked by the original part of the so-called "foundation charter" of Melrose Abbey, which records Walter as a witness.