Er - Gary - if you were a bit more specific you might get a more specific answer!
In general the AINSLIE variant of the AINSLEY surname is to be found mostly in the border counties of Scotland.Argueably its a derivative form of DE ANNESLEY, but I know of over 240 different ways of spelling the name so there really is nothing fixed!
There seems to have been a southwards migration along the lines of the drove roads from (in particular) Jedburgh and Dolphinston, with a spelling change to AYNSLEY once it got to Northumberland and northern County Durham, changing again to AINSLEY as it crossed Weardale and into Teesdale and northern Yorkshire.At around the same time a possibly independant clan of AINLEYs emerged in the area of Sheffield and Leeds, while the (possibly) original ANNESLEYs were based further south in Nottinghamshire.Later on the ANNESLEYs acquired titles and land in Ireland, and some became ANSLEYs - that spelling is now the principal one to be found in North America.
A few AINSLIEs and AYNSLEYs came south west into Lancashire and further south into the Potteries - its not however a common name on the western side of the Pennines.
Now - if you want to get more specific information, you're going to have to give more!What period are you looking at , and what names are you looking for?Do you have any specific dates and places or is your interest merely general (in which case you've got most of the potted answer above!)
Insofar as there is an AINSLEY (and variant) one name study, I coordinate the UK and Dominions end of it, while Bill Ansley looks after North America.My database has around 30000 AINSLEY related events on it now (and its constantly growing) and I am in contact with some 60 or 70 researchers with a similar interest.
I'd certainly like to discover what your interests are and to include your details and research requirements on the database, but to do so I need more from you!