As we met outside a church in the small Algarvian village of Praia de Luz, I was so shaken by the intensity of the sadness, despair, fear and torment in her tear-filled eyes that, for a long moment, I could find no words to say.

Clutching a small pink teddy bear belonging to Madeleine, the mother-of-three appeared almost doll-like in her fragility.

Her face haunted by unthinkable emotions, Kate could not bring herself to speak. She could only shake my hand and nod her head sadly.

Placing one arm protectively around his wife her husband, Gerry McCann, put his hand on my shoulder in welcome.

I was deeply moved by this small gesture of kindness to a complete stranger, especially at a time when the couple appeared to be feeling particularly low.

As he spoke he, too, had unshed tears in his eyes and the sadness etched on his face showed a man weighed down by an overwhelming burden.

Behind him, pinned on the door of the small, stone church, was a photograph of Madeleine.

Curious tourists stopped to look at the picture and paused for a moment of silent prayer or reflection.

Earlier in the evening, locals and foreigners joined the couple in the church for a vigil to pray for the little girl's safe return.

Throughout the service, Kate became visibly distressed and wept silently while her husband put his arm around her in a bid to offer her some comfort.

Outside the church, crowds of people gathered to offer words of encouragement to the young couple.

Public support is of major importance to the McCann's, with Gerry saying that the search for Madeleine is "nothing without the public", so it is of some comfort to them to know that their four-year-old has not been forgotten.

However, by keeping their campaign so public, they have opened themselves to adverse scrutiny and criticism, which must be taking its toll.

Watching them from behind as they walked hand in hand from the church and into the summer evening, passing a group of laughing children and tourists, they looked like any other young couple on holiday in Portugal.

But anyone who looks into their eyes will see a mother and a father haunted by the unthinkable, yet determined never to rest until they find their daughter.