50-1500 USD depending on specifics.
To determine the exact value of a Browning automatic 20 gauge shotgun made in Belgium, a couple factors would need to be taken into consideration. Some of these things are the age and condition of the shotgun.
$1600 if in excellent codition
100-1000 USD or so
Impossible to answer without the serial number.
You will have to call Browning with the sn to find out.
If that is the complete serial number, it was made in 1935. Value is $350-$650.
I will assume you meant to say Belgium vs England. Go to the link below to learn about Belgian Browning 16ga Values.
If your browning 16ga shotgun is a auto-5 then it was made by FN of belguim for browning in 1927.
It is the lightweight version of the Browning Auto-5 semi-automatic shotgun.