What's my name?

In the autobiography, frederick writes:

"The records of the Parish Church, St. Ann’s, Soho, bear witness that a little later the label “Frederick Vincent” was attached to me in solemn form, and certain promises were made on my behalf in which Miss Castell, a girl friend of my mother, took part: for a long time I thought that her name had been added to the others.

At school I was always known as “F.V.C. Brooks”, which my schoolfellows used to suggest savoured of a redundance not wanting in other directions : but on going to the Church Registry many years after I found that the extra name was a myth."

The extent of our author's mistaken belief regarding his own name has been discovered on obtaining a copy of his marriage certificate. Just how long the erroneous middle name persists after Frederick's school years, he fails to mention but long enough for him to spell it out for eternity on his wedding day.

Edit:
In fact, Fred's baptism does record Castell as a middle name.