However , such claims were not officially verified , thus Mallard continues to hold the official record .
It is very possible that around 1946 , the American Pennsylvania Railroad 's T1 class duplex steam locomotive could have attained faster operational speeds than Mallard .
Such claims were not officially verified , thus Mallard continues to hold the official record .
It is very possible that around 1946 , the American Pennsylvania Railroad 's T1 class duplex steam locomotive could have attained faster operational speeds than Mallard .