>>* Sorry Vianney, I don't understand how it works your code. Please can you
*>>* type
*>>* some lines more? Something with
*>
> Even simpler than before, using your example:
>
> \setuplayout[% default layout for all the pages
>  backspace=1cm,
>  width=middle]
>
> \definelayout[1][% set this layout on the first page
>  backspace=6cm]
>
> \definelayout[2][reset] % reset to the default layout starting from
> the second page
>
> \starttext
> \showframe
> \dorecurse{20}{\input dawkins \par \input knuth \par}
> \stoptext
>
> Vianney

It works like a charm! Many thanks.

Sam Qasbah