DS Saffron Saleh is an officer in the Manchester police force. She may even have known DI Sam Tyler before he was struck down by a car after his girlfriend was kidnapped.
Taking a Wold Newton approach, it's my contention that her cousin, Anvar Parvez, who is known as "Annie", lives in London and works as a medical examiner, a forensic pathologist for the London police department.
They could be first generation Britons, whose parents were immigrants from the sub-continent. And both girls saw their chosen fields as a way to repay their adopted homeland for allowing their parents to find a better life for themselves and their children.
The roles are not played by the same actress, as is usually the case in my theories of "relateeveety". Nisha Nayar plays Saleh and Amber Agar is Annie. But there is enough similarity in their appearance to suggest a close, yet not exact, relation between the two.
But because of the actress who plays her, Saffron Saleh could have been reincarnated far into the future as a programming executive on board the Gamestation space satellite. She joined the front lines in a vain battle against the Daleks when they invaded which cost the programmer her life. (However, she may have been brought back to life through the intervention of Rose Tyler as the "Bad Wolf".)
DS Saffron Saleh - "Cracker: A New Terror"
Dr. Anvar "Annie" Parvez - 'Murder City'
Gamestation programmer - 'Doctor Who' ("Bad Wolf" & "Parting Of The Ways")
DI Sam Tyler - 'Life On Mars'