Although there were Applebys in London in the earliest available parish records, the numbers increased dramatically over the next centuries - particularly during the latter part of the 19th century, as families and individuals sought employment in the growing capital.
Until very recently, it was also one of the most difficult areas to actually FIND your ancestors - with literally hundreds of parishes serving the tightly packed city. But the recent digitisation of the parish records held by the London Metropolitan Archives and the Guildhall Library has made the search for elusive ancestors so much easier!
My first impressions on collating the databases are that a number of the families that appear in the later censuses have arrived from other parts of England - I hope that you will discover some of your missing ancestors on the accompanying baptism, marriage and census files, even if your main area of interest is in another part of the country.
My own Appleby line comes from Bethnal Green, in the heart of London's East End - and over the past eight or nine years I have scoured each and every microfilm covering the City of London and the East End in an attempt to break down my brick wall. Along the way, I collected every Appleby/bee record I came across, but my original collection has increased tenfold with the release of the searchable baptism and marriage databases on Ancestry.co.uk.