Katrice Lee from Hartlepool was two when she vanished in 1981.
Her parents have always claimed that military police were slow to react to their daughter's disappearance.
Her father, Richard, says that although he welcomes the apology, he feels a public inquiry is the only way he will discover the truth.
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There are 66 candidates standing in the Tyne and Wear area in the General Election on June 8
Richard Vincent, 32, of Southmead Avenue in Blakelaw, was last seen in Newcastle city centre near to Spital Tounges.
There are 32 candidates standing in the Tees Valley area for the 2017 General Election