I am looking for a simple way to count the number of blocks found in the bitcoin network during the last hour at any given time.
What I can think of is to "getinfo" extract block and insert time, and block number in a Sql, this could be done once every hour and do a php calc, but is there a more simple way to do this?
You can't know for certain how many blocks have been found in the past hour, or when any particular block was found.
Blocks do have a timestamp, but miners are allowed to fill that timestamp with a time in the near past or near future when building the block. Therefore, that timestamp is only accurate to a time within a few hours.
The only other reliable time you have is the time that your wallet first hears about a block from a peer. There is a possibility of a delay between when the block is solved and when your wallet first hears about the block.