Siting a new birdbox

Having had a dead tree removed from our garden I am now struggling for a position  to install my bird box with combined camera . I’ve been wondering if buying a long post and concreting into the corner of the garden would work . I don’t see why not but just wondered what the experts thought , I’m also thinking of increasing the hole diameter to maybe entice the local sparrows or great tits as blue tits didn’t use it last year they used a box in my other tree . I know I will soon need to install it .
thanks in  advance .