The pair were found unresponsive at a property on Mayes Road on Sunday morning after concerns for their welfare were raised with emergency services.
Met Police officers and the London Ambulance Service were called to the house at 9.37am, on arrival, they found two people a 61-year-old man and a 31-year-old woman with stab wounds. The London Ambulance Service was called and both victims were pronounced dead at the scene.
While formal identification is yet to take place, we are confident the deceased are father and daughter. Their next of kin have been informed and are being supported by specialist officers.
Police arrested a 52-year-old man on suspicion of murder at an address in Huntingdon, Cambridgeshire on Sunday. He remains in custody.
Anyone with information should call 101, giving the reference 2183/28NOV.
Information can also be provided to Crimestoppers, anonymously, on 0800 555 111.