Simplexml : xpath with three conditions

I have a xml file like this :

<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
<channel>
<item>
	<city>London</city>
	<description>Trip</description>
	<link>page.php</link>
	<img>img.jpg</img>
</item>
<item>
	<city>London</city>
	<description>Trip</description>
	<link>page.php</link>
	<img>img.jpg</img>
</item>
<item>
	<city>Paris</city>
	<description>Trip</description>
	<link>page.php</link>
	<img>img.jpg</img>
</item>
.
.
</channel>
</rss>

If I want to select TRIP in LONDON, I do that :

<?php
$xml   = simplexml_load_file('file.xml');
$items = $xml->xpath('//item[city[contains(.,"London")] and description[contains(.,"Trip")]]');
foreach($items as $item){
echo ' txt ';
}
?>

If I want to select ONLY the first TRIP in LONDON, I do that :

<?php
$xml   = simplexml_load_file('file.xml');
$items = $xml->xpath('//item[city[contains(.,"London")] and description[contains(.,"Trip")]]')[0];
foreach($items as $item){
echo ' txt ';
}
?>

I try also 1 instead of 0, and this

> [position()=0]

it does not work.

What's wrong ?

I keep looking.
I have made several tests only with the position filter, for example :

<?php  
$xml   = simplexml_load_file('file.xml');
$items = $xml->xpath('//(/item)[1]');
foreach($xml->channel->item as $item){
echo '<div>....</div>';
}
?>

And it doesn't work.

I think I have a problem with this part, but I don't see where.

<?php
// Load the XML file
$xml = simplexml_load_file('your_xml_file.xml');

// Iterate through each "item" element
foreach ($xml->item as $item) {
    // Output the description and city
    echo $item->description . ' in ' . $item->city . '<br>';
}
?>

Unlike php, xpath indexing start from "1".

So either of these should get you only the first trip:

#indexing is indicated inside the xpath expression so it starts with 1:
$items = $xml->xpath('//item[city[contains(.,"London")] and description[contains(.,"Trip")]][1]');

or

#indexing is indicated outside the xpath expression so it's handled by php and  starts with 0:
$items = $xml->xpath('//item[city[contains(.,"London")] and description[contains(.,"Trip")]]')[0];

I found this way (to find only the first one) :

$xml   = simplexml_load_file('file.xml');
	$i = 0;
	$nb_affichage = 1;
	$items = $xml->xpath('//item[city[contains(.,"London")] and description[contains(.,"Trip")]]');
	foreach($xml->channel->item as $item){
	echo '<div> txt </div>';
	if(++$i>=$nb_affichage)
	break;
	}

It's definitely not the best, but it works.
If anyone has a better idea, I'm still interested.