Show series field when citing report

Question

The exact opposite of this question, I'd like to show the "Series" field when citing working papers, which I currently do using item type "Report".

(I use report because Zotero doesn't have the techreport field, which this answer suggests using.)

The resulting citation looks fine, but I need to show the working paper series it belongs to.

How can I add this field to my bibliography?

foo.bib

@report{collier_military_2002,
  location = {{Washington D.C}},
  title = {Military {{Expenditure}}: {{Threats}}, {{Aid}} and {{Arms Races}}},
  number = {WPS2927},
  series = {Policy, Research Working Paper},
  institution = {{World Bank}},
  date = {2002},
  author = {Collier, Paul and Hoeffler, Anke}
}

foo.tex

\documentclass{report}
\usepackage[backend=biber]{biblatex}    
\addbibresource{foo.bib}    
\begin{document}    
I love to cite \textcite{collier_military_2002}.    
\printbibliography    
\end{document}

Which produces:

Answer 1

@reports don't support the series field. Instead they have a type. I think in this case type+number is more appropriate than series+number. Incidentally, even http://documents.worldbank.org/curated/en/162611468739486410/ lists "Policy Research Working Paper" as "doument type".

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[backend=biber]{biblatex}

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@report{collier_military_2002,
  location    = {Washington, DC},
  title       = {Military Expenditure: Threats, Aid and Arms Races},
  number      = {WPS2927},
  type        = {Policy Research Working Paper},
  institution = {World Bank},
  date        = {2002-11},
  author      = {Collier, Paul and Hoeffler, Anke}
}
\end{filecontents}

\addbibresource{\jobname.bib}

\begin{document}
\textcite{collier_military_2002}.
\printbibliography 
\end{document}