Sir Topham Hatt (Alias "The Fat Controller", "The Fat Director" and "The stout gentleman"), is the director of the North Western Railway.

According to the Rev W. Awdry, "The Fat Controller" has been three different people, the first, was simply Mr Topham (1888-1956), married to Lady Jane Hatt, he ended his service around 1956. As of this date, His son, Sir Charles Topham Hatt (1914-?) then took over. Sir Toppham Hatt retired in 1984 and placed the North Western Railway into his son Stephen's hands, Stephen Topham Hatt was born sometime between 1941 and 1946.

It has been put forward that Mr Topham's holiday in 1950/51 with his wife and grandchildren, Stephen and Bridget; was to give his son Charles an opporunity to prove to his father that he could continue the family legacy, as well as to have a relaxing time out of the office.

There is an issue concerning the "Sir Topham Hatt" printed on a case in "Percy and the Trousers", set in 1950, if one is to believe Rev W. Awdry then Mr Topham is the director of the NWR. He is without a Knighthood and does not use his wife's second name; how then, can the trunk be accurate? The answer is that the trunk belongs to his son, Sir Charles Topham Hatt, who would have been 36 at the time, relatively young for a Knighthood. Another small issue arrives just after this, when Mr Hatt states that the trousers coiled around Percy's funnel are his. However they may not have burst from the case marked "Sir Topham Hatt", but from one of the other trunks on the porters trolley. Either that or his son had 'borrowed' them.