We have applied for PR in Singapore. I had worked in a British firm for 8years till 2009. If we mention that in our application, will Singapore government enquire or verify with that firm . Anybody applied for PR and had similar background ?

I reckon when dealing with these official application forms, best to declare everything as truthfully as you can. If they check and you haven't declared truthfully, your application might be rejected so no harm declaring it. You seem concerned about declaring that you used to work with the firm? Is there a reason why?