I am always happy to provide a work reference for someone who needs one. Obviously I will have worked with the person in the past and can attest to their skills, knowledge and strengths.
But surely it's not too much to ask of a former work colleague or employee to contact me first. To ask if they can give my name as a referee. To get a call out of the blue from someone in the HR department or from a recruitment agency is not appreciated.
Sometimes I struggle to remember who they are actually referring to. Last year I received a call from an agency in Australia about someone I worked with over 10 years ago. Surely that person would now have a more recent referee to provide.
I have not always given permission in the past when asked if my name can be given as a referee. That's on the occasions when I have been contacted. I have simply said it would be better if they got someone else - a response that hasn't always been well received. But if I wouldn't re-employ them why would I recommend them to someone else? Pass the problem on. But most times I do want to help because someone is trying to get a job after all.
But over the last few years I think HR departments and recruitment agencies are becoming more demanding in their reference checks. I believe they want to recommend and hire the best person for the job. So they should take reference checking seriously and there have been some well publicised cases in the past where job applicants have lied about their qualifications and suitability for a job. Thorough reference checking might have seen these blunders avoided.