public  class HelperClass  // Rename me
{
    private  Dictionary<string,tbl_Policy> PolicyCache = new Dictionary<string,tbl_Policy>();
    private  Dictionary<string,tbl_Client> ClientCache = new Dictionary<string,tbl_Client>();
    public  tbl_Policy FindPolicyFromPolicyNumber(string policyNumber)
    {
       if (PolicyCache.ContainsKey(policyNumber)) {
         return PolicyCache[policyNumber];
       }
       var pol = ctx.tbl_Policy.Include("tbl_Client").Single(f => f.txt_policyNumber == policyNumber);
       PolicyCache.Add(policyNumber, pol);
       ClientCache.Add(policyNumber, pol.tbl_Client);
       return pol;
    }

    public  tbl_Client FindPolicyFromPolicyNumber(string policyNumber)
    {
       if (ClientCache.ContainsKey(policyNumber)) {
         return ClientCache[policyNumber];
       }
       var client = ctx.tbl_Client.Single(f => f.tbl_Policy.Any(g => g.txt_policyNumber == policyNumber));
       ClientCache.Add(policyNumber, client);
       return client;
    }
}