Because apart from Wanderers F C (NOW DISBANDED) Blackburn are the only football club to win the F.A cup three times in a row so they have been given that right.
They Won the FA cup 3 times in a row and the English league at the time could not pay for the prize so they allowed Blackburn to put their badge on the corner flags. The only team allowed to do so.
4 corner flags. 2 linesmen offside flags.
Flags that are allowed in to many many places
Those who have triangular flags have won the FA cup. any one can use any shape of flag as long as you have a flag on top of corner pole - many clubs use Pennant style or Moon Flags to make them stand out you do not need to have won a cup or league competition
No
The size of the badge may be helpful. If it is small, this could be a collar brass or a specialty badge worn on the sleeve. For example, some in the Signal Corps wore a brass crossed flags on the sleeve, I believe. I will search some references.
blue and gold
The only official flags associated with soccer are the four corner flags. The Laws of the Game (LOTG), specifically Law 1, do not prescribe a specific size for the cloth on the flags. The corner flag poles must be at least 1.5m (5 ft) tall with a non-pointed top.
foxfinearts.com
they help show whether the ball went out for a corner kick or throw in
Triangular corner flags are given to winners of the FA Cup. Cardiff City beat Arsenal 1-0 in 1927 and are the only welsh team (so far) to have won the trophy.
The flags (banderas) of the nations of the Caribbean, Central America and South below, with a blue patch in the top corner containing a white five-pointed star.