Hi,

I've experimented this morning with the solutions suggested by Wolfgang 
and Alan in reply to my post.

The solution is really quite simple as suggested by Wolfgang i.e. 
\centerbox{..}.  I have applied this to the code and I now have three 
different solutions to my initial problem. The Joy of ConTeXt!

Thanks again Wolfgang and Alan.

Best Wishes

Keith McKay

Here is the code showing the three solutions which others may find useful.

\setuppapersize[A4,portrait]%[A4,portrait]

\setuplayout

[backspace=2.5cm,

topspace=1cm,

height=28cm,

width=17cm,

header=0cm,

footer=0.75cm,

]

\setuppagenumbering[state=start,alternative=doublesided,location=margin]

\useMPlibrary [dum]

\starttext

%%% Me %%%

\showframe [text] [text]

\definelayer[test3]

\setlayer[test3][]

\centerbox{

{\startcombination[nx=3,ny=1,distance=15mm,after=,location=middle]

{\externalfigure[dummy]}{}

\rotate[rotation=90]{\externalfigure[dummy]}{}

{\externalfigure[dummy][]}{}

\stopcombination}

}

\flushlayer[test3]

\page

%%% Wolfgang %%%

\centerbox

{\bTABLE[frame=off,offset=7.5mm,align={middle,lohi}]

\bTR

\bTD

\externalfigure[dummy]

\eTD

\bTD

\rotate[rotation=90]{\externalfigure[dummy]}

\eTD

\bTD

\externalfigure[dummy]

\eTD

\eTR

\eTABLE}

\page

%%% Alan %%%

\centerbox{

\startparagraph [align=middle]

\startframed [frame=off,offset=\zeropoint]

\startcombination [nx=3,ny=1,distance=15mm,after=,location=middle]

{\externalfigure[dummy]}{}

\rotate[rotation=90]{\externalfigure[dummy]}{}

{\externalfigure[dummy][]}{}

\stopcombination

\stopframed

\stopparagraph

}

\stoptext

On 16/03/2023 19:50, Keith McKay wrote:
> Thanks Wolfgang and Alan! I will experiment with them tomorrow.
> Best Wishes
> Keith McKay
>
>