Convert Field To FieldLookup using ClientContext

Question

I need to get a FieldLookup from a list (already queried). First line in the below code errors out "Unable to cast Field to FieldLookup". Yes, the field I am trying to retrieve is a lookup field only. Any help?
list - A sharepoint list
ctx - ClientContext instance

var fieldLookup = (FieldLookup)list.Fields.GetByInternalNameOrTitle("ALookupField");  
ctx.Load(fieldLookup, (s) => s.LookupList);  
ctx.ExecuteQuery(); 

Answer 1

Found a hack to get the lookup list id.

    var field = list.Fields.GetByInternalNameOrTitle("ALookupField");  
    ctx.Load(field, (s) => s.SchemaXml);  
    ctx.ExecuteQuery();  
    var lookupListId = XElement.Parse(field.SchemaXml).Attributes().First(s => s.Name == "List").Value;  

Logically one would think that this List prop in schema corresponds to the list the field belongs to, but the fact is, it corresponds to the LookupList. That's MS way.