It might help to add some indenting and use the forum's [noparse]
...
[/noparse] tags so we can see what's going on:
array (
'id' => '34970',
'agency_branch' => 'ELLESMERE PORT',
'house_number' => '2',
'address1' => 'Rosset street',
'address2' => '',
'town' => 'LIVERPOOL',
'county' => '',
'postcode' => 'L6 4AW',
'reference' => 'H78',
'bedrooms' => '0',
'receptions' => '0',
'max_occupancy' => '0',
'max_tenancies' => '1',
array (),
'bullets' => array (),
'images' => array (
0 => array (
'image_name' => 'https://***************************.jpg',
'thumbnail_image' => 'https://***************************.jpg',
'Target'=> 'Exterior',
),
1 => array (
'image_name' => 'https://***************************.jpg',
'thumbnail_image' => 'https://***************************.jpg',
'Target'=> 'Exterior',
),
2 => array (
'image_name' => 'https://***************************.jpg',
'thumbnail_image' => 'https://***************************.jpg',
'Target'=> 'Exterior',
),
3 => array (
'image_name' => 'https://***************************.jpg',
'thumbnail_image' => 'https://***************************.jpg',
'Target'=> 'Exterior',
),
),
'epc_location' => '',
)
So, if you want the last thumbnail, it would be [FONT=Courier New]$data['images'][3]['thumbnail_image'][/FONT].