The 1861 census shows an Alex McGregor at Bruce, Bruce, Ontario. He is the head of the household and is married. Essentually the same is provided for 1871. I found a census for 1891 for an Alex Mcgregor at Owen Sound, Grey North. It shows his wife Ann and son John living with him. Not certain if these all are the same Alex McGregor.
It seems Alex sr. and son Alex are buried at Culross-Tesswater Cemetery. Ann was living with her daughter Magaret McGregor-McLeod in Harriston at the time of her death in 1911.