Third Secret, The

Mrs. Bales (Freda Jackson) arrives at the house where Dr. Whitset lives with his daughter Catherine. Strand-on-the-Green in London W4.

Fortunately the tide was out for some decent comparison shots. SJ

The housekeeper lets herself into the consulting room to find the Doctor dying on the floor and whispering "Blame no one but me."

Hmm, doesn't look the same at all. SJ

Sir Frederick Belline (Jack Hawkins) is shocked to read about his Doctor's apparent suicide. The Chapel undercroft, Lincoln's Inn WC2. The location also features in 'Oxford', 'Mr. Holmes' and 'Tom Jones'.

I found this quite hard to align correctly. SJ

Dermot McHenry (Charles Lloyd Pack) asks the respected judge if he's alright.

Pity about the parking. SJ

American news reporter Alex Stedman (Stephen Boyd) finds his way to Dr. Whitset's riverside home. In the left distance is a gas holder at Brentford Gasworks whilst the Standpipe Tower of Kew Pumping Station rises to the right of centre.

The tower is now dwarfed by "luxury" riverside development. SJ

Alex questions whether his Doctor did committed suicide. Strand-on-the-Green in The location was also seen in ‘Four in the Morning’, ‘Father Brown’, ‘The Jigsaw Man‘ and ‘Darling’.

Reassuringly architecturally frozen after fifty years. SJ

The commentator approaches the Doctor's house. Strand-on-the-Green with Kew Railway Bridge in the right distance.

Can't match the lens trick of bringing the background forward. SJ

Outside her former home, Catherine Whitset (Pamela Franklin) looks down towards Alex as he walks along the river's shore.

The same scene now. SJ

The Doctor's teenage daughter calls on Alex to ask for his help after telling him that her father didn't kill himself.

The young girl makes her way into the building.

The camera tilts up the apartment block to the windows behind which Alex is wrecking his flat in frustration and rage.

School friends tell Catherine not to walk near her old house. Facing west on Broomfield Road in Richmond.

That's the wall. SJ

Catherine tells them that she walks that way to her aunt and uncle's house. Broomfield Road at the corner of Princes Road.

Turn around and there we see top of the wall alterations. SJ

After falling out with her classmates, Catherine is almost run down by a passing car. Broomfield Road looking into Princes Road.

Same curve. SJ

More schoolgirls wait around the corner and Catherine pushes past them. The street sign is not a prop, this is Princes Road in Kew.

Some elegance has been lost in the replacement sign. This scene is slightly out of topological kilter with the previous and next. SJ

The fourteen-year-old looks behind her before increasing her pace. Facing north on Kew Gardens Road, Richmond.

I took a step or two back to incorporate the sign. SJ

Catherine breaks into a run. The entrance to Atwood's Alley at the corner of Kew Gardens Road and Leyborne Park in Richmond, Surrey.

Yep, bang on. SJ

Looking to the junction of Kew Gardens Road, Broomfield Road, Leyborne Park, Station Approach and Sandycombe Road from Atwood's Alley.

Yes, looking south. SJ

Atwoods Alley in Richmond.

Same gate posts to a back garden on the right. Otherwise it would have been quite hard to pinpoint as it's a long alley. SJ

When she reaches the river, Catherine stops running and sits in a shelter, where Alex joins her a few moments later. This area is now occupied by Upper Mall Open Space, a small public garden on the edge of the Thames where the West Middlesex Water Company’s waterworks once stood.

Yes, unrecognisable now. And what happened to that Andersen statue in the grab? The bench on the right stands as a poignant tribute to Theo Knowles, a former pupil of mine. SJ

As the two walk together, Alex explains that the housekeeper told him that Catherine would be there. This appears to be a garden situated between the waterworks and Black Lion Steps in W6. In the right distance stands Hammersmith Bridge. The pathways along this stretch of the Thames also feature in 'The Water Gipsies’ and ‘Murder at 3am’ while, with redeveloped surroundings, a similar view was filmed nine years later for 'The Love Ban'.

In the left distance, one can now see the Old Ship pub which would have been blocked from view by the Hammersmith Pumping Station: there are arched remains to the left out of shot. SJ

Alex is impressed by Catherine's knowledge of Hans Christian Andersen. This sculpture of Hans Christian Andersen by Georg J. Lober appears to be a copy of the original that stands in Central Park, New York.

Catherine tells Alex that her father said everyone has three secrets, "The ones they won't tell people, the ones they won't tell themselves and . . . . "

The youngster writes a line from Shakespeare on the wall and proclaims that she likes Alex now that her father is dead. Black Lion Steps leading down from Upper Mall and Hammersmith Terrace in W6.

Beams have been added since. SJ

The television reporter discloses that his daughter is also dead. The Thames, upriver from Hammersmith Bridge in Richmond with the West Middlesex Waterworks, later known as Hammersmith Pumping Station, on the north bank. The buildings were demolished in 1965.

The Thames at low tide now. SJ

Alex leaves Catherine to go home after she says that she will give him a list of her father's private patients next time they meet. Black Lion Steps with South Black Lion Lane at the top.

And in both shots one can just see the point of the Black Lion pub. Well served, this area, for pubs. SJ

Alex seeks out Anne Tanner (Diane Cilento), the second of three patients on the list.

Could this be Inner Temple Gardens EC4 with Paper Buildings in the right background asks John Tunstill. He may well. I say close, but now revealed as Lincoln's Inn Fields, with Lincoln's Inn library in the background, WC2. SJ

When talking with her, the reporter discounts Anne as being Whitset's murderer.

And Lincoln's Inn Fields again just a little further south from a scene in The Day of the Triffids. SJ

Sir Frederick is the next patient to be questioned. Looking out onto New Square in Lincoln's Inn. To the centre is a building also seen in 'Home to Danger', 'A Cry from the Streets' and 'Eight O'clock Walk'.

Much the same now. SJ

After Anne's body is found along with a note confessing her responsibility for the death of Dr Whitset, Catherine looks down to a shocked and despondent Alex. Strand-on-the-Green in Chiswick W4.

Tricky: the railing has gone. I don't think the post is the same as one of those further one as the background goes wrong! SJ

The two talk for a while before Catherine recites the names of famous people who have lived along the waterfront. Strand-on-the-Green was also seen in 'Darling', 'The Jigsaw Man', 'Father Brown', 'Goodbye Mr Chips (1969)' and more.

Far fewer trees. SJ

Alex and Catherine climb onto the footpath. Looking to the west from Strand-on-the Green, Chiswick, The Standpipe Tower of the former Kew Pumping Station now forms part of the London Museum of Water and Steam on Green Dragon Lane, Brentford.

Roundabout here. SJ

Questions are asked about a house in Colchester that Catherine's father used to visit. Strand-on-the Green once more.

Trying to match that white wall on the right. SJ

Alex visits Whitset's country retreat where he finds the Doctor's private files, including his own and one for a fifth, unexpected patient.