In the novel They do it with Mirrors, Edgar Lawson was the name of one of the juvenile delinquents, who arrived about a month before the story begins (after the last meeting of the board for the Gulbrandsen trust), who is often in the house and on the grounds, and who works closely with Lewis Serrocold.
Edgar drives to Market Kindle station to meet Miss Marple. She notices that his voice has an "unexpectedly dramatic quality", but that his personality does not match his voice, as it is less important, or almost insignificant. She also notices that his eyelids tend to flutter nervously.
Edgar tells Miss Marple in confidence that he is the son of Winston Churchill. He says that his father has enemies, and that they are against him too, spying on him and making things go wrong for him. Lewis Serrocold later told Miss Marple that Edgar was an illegitimate child, and had been brought up in difficult circumstances. Edgar had started romancing about his father, and then about himself, and wearing uniform and decorations he was not entitled to. However, Lewis considered that Edgar had improved since coming to the Institute.
On the night of the murder, Edgar bursts into the Great Hall at Stonygates. He accuses Lewis of spying on him, and working with his enemies against him. Lewis takes him into the study, and the door is locked. Edgar continues to shout at Lewis, and threatens him with a gun. He fires two shots, which hit the wall behind Lewis' desk.
It is later revealed that the scene between Edgar and Lewis in the study was staged. Lewis left the study by the window, and ran along the terrace to Christian Gulbrandsen's room, to kill him. Edgar remained in the study, doing two voices so that it would appear that both of them were still in the study.
When the police question Edgar, he loses his nerve, and runs away. He runs to the lake, and jumps into a punt. The punt is rotten, and sinks. Edgar struggles in the water, as he does not know how to swim, and Lewis goes in to rescue him. However, they both get entangled in reeds, and get into difficulties. The police eventually get them out, and attempt artificial respiration, but it is too late.
In chapter 23, Miss Marple later mentions that she suspected that the persona "Edgar Lawson" was an assumed one. Earlier on, the police had learnt that there was real Edgar Lawson, the son of a poor class respectable woman in Plymouth and a foreign seaman. The police checked up and confirmed his case history. But the young man at Stonygates reminded Miss Marple of Leonard Wylie who was just as devoted to one he calls his father. Carrie Louise agreed with this and noted a likeness in the appearance of "Edgar" and Lewis Serrocold. She added that Lewis had once had a short infatuation for an actress before his present marriage. The relationship was not successful, the actress was a "gold digging" sort but Carrie Louise had no doubt that the "Edgar" at Stonygates was Lewis' son. Miss Marple concurred as this explained "everything."
Murder with Mirrors (1985)
In Murder with Mirrors (1985), Edgar Lawson is played by Tim Roth. Here he also actively helps Lewis Serrocold set up the illusion for the murder like in the original novel. Miss Marple considered that he knew how to play his part well because he was a member of the Stoneygates theatre group. He had once played a part in a production of "The Mousetrap". Miss Marple also compared him to Leonard Wylie and felt his behaviour was overdone and unconvincing. Here Miss Marple stated that Edgar considered Lewis as most like a father. Unlike the book and other adaptations, it was never confirmed if Lewis was actually his father.
In Murder with Mirrors (1985), Gina is played by Liane Langland. Gina's husband's name is changed to Walter Markham. Gina's parents died in an aircrash. Miss Marple says she had refused to travel in an aeroplane ever since that accident.
BBC's Miss Marple
In the BBC 1991 adaptation of the novel which formed part of the Miss Marple series, Edgar Lawson is played by Neal Swettenham. The portrayal is quite close to the novel. However, here, "Edgar Lawson" is not an assumed persona but his real name. Miss Marple actually sends Griselda Clement to Somerset House and from the records there she confirms that Edgar is indeed the son of Lewis Serrocold. In the novel, the relationship was suspected but never confirmed.
In the BBC 1991 adaptation of the novel which formed part of the Miss Marple series, Gina is played by Holly Aird. Her background is similar to that in the book, except that she met her husband during the Korean War, suggesting that she had volunteered as a nurse during that war. Here both Alexis and Stephen Restarick try to chat her up and she is seen often going about with them. However Carrie Louise tells Miss Marple that Gina really does love Wally. Miss Marple does not believe it at first until she sees Gina with Wally and his newly purchased horse. Miss Marple then realises that Carrie Louise was actually a very perceptive person, and she drew on her observations for several important leads.
ITV's Agatha Christie's Marple
In the ITV 2009 adaptation of the novel as part of their Agatha Christie's Marple series, Edgar Lawson is played by Tom Payne. His role is similar to that in the book. He dies when trying to swim across the lake instead of using a rotted boat.
In the ITV 2009 adaptation of the novel as part of their Agatha Christie's Marple series, Gina is played by Emma Griffiths Malin. Here she is not the adopted granddaughter but the adopted daughter of Carrie Louise. Mildred is much younger in this adaptation and is her sister. There is tension between the two as Mildred thinks that Gina has monopolised Carrie Louise's affections. Mildred plants a newspaper article about the murderess Katherine Elsworth who is Gina's real mother. This upsets Gina tremendously. During an amateur theatrical staged at Stoneygates, Gina (who in this adaptation takes part in drama) puts on a blonde wig to resemble Ellesworth, perhaps as a way of expressing her resentment that this secret had been hidden from her. Gina's feelings for her husband Wally Hudd are complex. Her affection for Stephen Restarick seems real--they kiss secretly in the theatre. But she does defend Wally when the police are about to arrest and take him away. She argues that anyone could have left the drawing room unseen by using a secret door which she shows to the police. At the end of the show she chooses to go with Wally and she later writes to Miss Marple that she had followed him to Wyoming and that they had prospered.