\documentclass[a4paper]{letter}
%%%% choose one of the following 4 lines to set colour and/or date style,
\usepackage[myukdate,colour]{ilab-letter} % Day, num Month year, and colour (use lp2)
\addtolength{\topmargin}{2cm}
%\usepackage[]{leedsletter} % Black-and-white, with US style date Month num, year
%\usepackage[myukdate]{leedsletter}
%\usepackage[colour]{leedsletter}
%%%% end
\department{{\bf School of Mathematical and Computer Sciences}\\[26pt]
Heriot-Watt University\\
Edinburgh$\;$ EH14 4AS $\;$ UK\\[12pt]
%%%% edit the following three lines to suit you. If you add a line, then 38pt -> 26pt above
~~ +44 (0)$\,$131 451 XXXX\\
%F~~ +44 (0)$\,$113 343 5090\\
~~ XXXXX@hw.ac.uk\\
~~ www.macs.hw.ac.uk/XXXXX}
%%%% end
\alignit{30pt} %% tweaking parameter - probably no need to change.
%%% need to edit user info
\signature{your signature here\\[5pt]
your title here}
%\\[15pt]
%Heriot-Watt University\\[5pt]
%Edinburgh }
% end personal details
%%%%%%%%%%%%%%%%%%%%%% a bove this line is sender specific %%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%% and probably only needs edited once %%%%%%%%%%%%
%%% what follows is letter specific
% the next line is specific to this letter, and may be used for "short" letters
\skipit{1} % this amount (default = 1.7) increases 2 gaps: address-date-opening
\begin{document}
\begin{letter}
%{Address line 1\\
%Address line 2\\
%Address line 3\\
%Address line 4}
%% if this is a ``short'' or long address, then alter \skipit above
\vspace{-4cm}
%\opening{To whom it may concern,}
\opening{ }
\medskip
\centerline{\bf Letter of reference for XXXXX}
% \\
%in support
%of a research degree in Computer Science/ Cognitive Conversational
%Interfaces.}
\medskip
body of letter here
\closing{Yours sincerely,}
\end{letter}
\end{document}