EF 6 - One To Many Mapping Always Null

I can't seem to resolve my mapping issue; The relationship is one user may have many venues, A venue must have a user.

My venue class looks like:

public class Venue : BaseObject, IBaseObject
{
    [Required]
    public virtual User Owner { get; set; }

    [Required]
    [MaxLength(50)]
    public string Name { get; set; }
}

My User class looks like:

public class User : BaseObject, IBaseObject
{

    [Required]
    public string Name { get; set; }

    [Required]
    [DisplayName("Email")]
    public string EmailAddress { get; set; }

    [Required]
    public string Password { get; set; }

    public bool Active { get; set; }


    public virtual ICollection<Venue> Venues { get; set; } 
}

DbContextClass as requested

 public class SystemContext : DbContext, IDbContext
{
    public SystemContext() :
        base("SystemContext")
    {
        Database.SetInitializer<SystemContext>(null);
        Configuration.ProxyCreationEnabled = false;
        Configuration.LazyLoadingEnabled = true;
    }


    public SystemContext(string connectionstringname = "SystemContext") :
        base(connectionstringname)
    {
        Database.SetInitializer<SystemContext>(null);
        Configuration.ProxyCreationEnabled = false;


    }
    public new IDbSet<T> Set<T>() where T : class
    {
        return base.Set<T>();
    }


    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);
        modelBuilder.Entity<User>().HasMany(x=>x.Venues);
    }



    public DbSet<PublicQueries> PublicQueries { get; set; }
    public DbSet<Venue> Venues { get; set; }
    public DbSet<User> Users { get; set; }
}

When I load the User class from the database Venues always seems to be null?

I've done something similar before but can't remember how I resoled this.

Thanks