# Remove first name on in-text citation

I am trying to sort out the citation and bibliography for a paper, and make it conform with the style-sheet from my university, which is a version of the Chicago style.

There are chicago-styles available both to Natbib and Biblatex, but I can't get any of the do do what I want: Display only last name on "in-text" citation (unless there are many different authors with same last name), and then the full name in my bibliography.

Here's a MWE:

\documentclass[a4 paper,12pt]{report}
\usepackage{graphicx}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{times}

\usepackage[english]{babel}

\usepackage[
authordate,
backend=biber,
natbib,
maxbibnames=99,
]{biblatex-chicago}

\usepackage{csquotes}

\begin{filecontents}{mybib.bib}
@BOOK{orton,
title = {Survey of English Dialects},
publisher = {Leeds: Arnold},
year = {1962},
author = {Orton, Harold},
volume = {IV},
date-modified = {2014-04-24 18:41:22 +0000}
}
\end{filecontents}

\begin{document}

This is a quote \citep{orton} .  And then the second quote by the same person     \citep{orton}

\printbibliography
\end{document}


As you can see if you try to run this, the in-text citation provides the full name like this (Orton, Harold 1962), while I simply want (Orton 1962). The bibliography looks fine.

John