I know I will sound like sour grapes here but agree with expatofff, its not just the nature of being an ex-offender its more to do with how the British see people and react to them so no petition will ever change this, the politics, government, police and society have already concluded this so its safety first, trouble afterwards approach. As a British people this is how we roll and progress I prefer to call it covering the backside approach, while we should not have this attitude it exist and defines the British.
Lets take Jeremy clarkson he should be in prison for assault or even at the very least with a criminal record, but nope the british public have to have what they want so they petition away in the millions, they still fail yet get him back anyhow, we may ask how? Clarkson entertains millions and brings a smile to there depressing lives so what can an ex-offender offer a potential employer or the British public ?
Short answer is nothing since millions of clean record or non ex-offenders are applying for the same job or trying to do the same thing.
The only thing anyone can strive for is the move away from UK, go self employed or get an job which ever way possible and move on, life has to continue because were not jeremy clarkson but an interesting after thought is what if we were a little like jeremy clarkson ?