\usepackage {colortbl}
\setlength{\extrarowheight}{2mm}
\setlength{\tabcolsep}{2mm}
\newcolumntype{G}{>{\columncolor[gray]{0.8}[0pt][0pt]}c}

\begin{tabular}{|l|c|G|c|G|c|G|c<{\textsc{GBP}}|}
\hline
 \multicolumn{3}{>{\columncolor[gray]{0.5}}l}{\textsf{LONDON}}
&\multicolumn{3}{>{\columncolor[gray]{0.5}}r}{\textsf{Price}}
\\[1pt]
\hline
Sydney  & OG4G &Thu Oct 10 &Mon Oct 21 or 28 &11 or 18 days &999\\
       &      &Thu Oct 17 &Mon Oct 21 or 28 & 4 or 11 days &999\\
       & OG7A &Sun Oct 13 &Mon Oct 21 or 28 & 8 or 15 days &999\\
       &      &Sun Oct 20 &Mon Oct 28       & 8 days       &999\\
\hline
\end{tabular}