Graham, I totally agree with you. I even wonder if this thread is in the wrong place as it isn't purely about Middlesbrough and Yorkshire history. I really can't understand the computer logic in the results that I was getting. I worked in IT until I retired and I understand the procedures of searching. Although Middlesborough is only a small part of my research, it did come as a surprise to me the day that I realised how it should be spelled. Ironically one of the family name's I am researching is Loughborough, and there is a whole branch which at some point in their history somehow had it changed it to Loughbrough.
Equally worrying is the fact that I got 177 hits until I specified either spelling of Middlesbrough as well, and got 0. Ironically I was searching in Middlesborough for alternative and incorrect spellings of another name and that is what made me discover these anomalies.
Martin