$re = '/\[\[Image:[^]]+link=[^]]+]]/';
$str = '$t = [[Image:United Kingdom images gbr image031 jpg.png|141px|link=HomePage|United Kingdom images gbr image031 jpg.png]]
[[Image:United Kingdom images gbr image030 jpg.png|141px|United Kingdom images gbr image030 jpg.png]]
[[Image:United Kingdom images gbr image031 jpg.png|141px|link=Contact|United Kingdom images gbr image031 jpg.png]];
<span class="United Kingdomtemplate_colour">Additional remarks</span><br> <br> Green sign with white and yellow text with blue plate with white text displaying that the indicated direction(s) lead to a motorway. [[Image:United Kingdom images gbr image031 jpg.png|141px|link=Home Page|United Kingdom images gbr image031 jpg.png]]<br>White sign with black text with blue plate with white text displaying that the indicated direction(s) lead to a motorway. [[Image:United Kingdom images gbr image046 jpg.png|292px|United Kingdom images gbr image046 jpg.png]]<br> <br> <span style="vertical-align: top;">White sign with black text with blue plate with white text displaying that the indicated direction(s) lead to a motorway. </span> [[Image:United Kingdom images gbr image2550 jpg.png|368px|United Kingdom images gbr image2550 jpg.png|link=Contact]]';
$subst = "[noinclude]$0[/noinclude]";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php