The former television executive has only gained a three-month extension to his £125,000-a-year agreement to run the country's jails, before going on what has been described as a "one more escape and you're out" monthly contract.
As shock at the unprecedented contract reverberated around the Prison Service, Home Office sources suggest that the new deal is a political compromise.
Michael Howard would have been open to criticism for granting a long extension to Mr Lewis's contract following the embarrassing escapes.
On the other hand, he would have been subject to ridicule if he had terminated the contract. That would have been a tacit admission that the controversial appointment of a man who had no experience of prisons had failed.
But yesterday Mr Howard was attacked for introducing instability into a service already suffering from low morale, prison overcrowding and the recognised difficulties of privatisation.
Terry McLaren, vice-chairman of the Prison Officers' Association, said: "He's on probation, it is as simple as that. And that is very unhelpful. We want and need someone who is going to be there for some time, who knows what they are doing and who enjoys the confidence of everybody."
Harry Fletcher, assistant general secretary of the National Association of Probation Officers, said: "The contractual mess is a logical outcome of an inexperienced political appointment."
Mr Lewis's initial three-year contact, due to end in January 1996, contained an option for a two-year extension to January 1988. According to a parliamentary written reply yesterday, he was informed last month that the contract would not be extended and his existing arrangements with the Home Office were changed so that after April 1996 he will be on a monthly rolling contract.
However, it appears that behind the scenes some greater indications of confidence have been given to the director- general, who as head of the new Prison Service Agency has undoubtedly taken the blame for the jails' ills that would otherwise have been levelled at ministers.
In a letter to governors written yesterday, Mr Lewis, who is currently touring maximum security jails and boot camps in the United States, said he was able to confirm he had agreed to continue as director-general for up to two years - until April 1997 - and that his departure in the meantime was subject to a year's notice either side.