Hi,I believe the name originated in Derbyshire and Notingham Shire in about 1450-1550.There is a church, I think it was Broughton or something like that where a number with a similiar spelling were married and baptised.The church is near the border of the two shires.
I looked in the records in St. Mary's Church in Nottinghamshire in about 1985 and found several references.One was to an Alsobrook (can't remember the spelling) who had killed someone with a knife and the constable or coroner had something to do with it. I'm hazy on this and the copies I made have since faded. The handwriting was very hard to make out. I don't know how far you are from Nottingham Shire but we certainly need someone to go there and research further.By the way, there was someone connected with Parliament during the war (or '40s) I think.I seem to remember that his name was Simon Alsobrook, but I've never found another reference.