The projects aim to give prisoners realistic training and relevant job skills to help them into employment on their release.
The first conference centre, based in the grounds of Highpoint women's prison in Suffolk, has already begun taking commercial bookings at pounds 80 a head and is expected to generate a turnover of pounds 200,000 a year.
At Styal prison in Cheshire, prisoners have been given skills in "teleworking" which are being used to transform a self-contained unit at the prison into a commercial call centre. The prison has trained 20 women in telephone answering, data inputting and word processing and the unit has already been privately-hired to carry out telephone surveys of prices charged by businesses for various goods.
Phil Wheatley, the deputy director general of the Prison Service, said such "realistic" work would help to prevent the prisoners from reoffending when they left prison. "It is a key objective for the prison service to provide prisoners with genuinely valuable skills on release," he said.
At Highpoint, women convicted of offences ranging from drug supply to manslaughter, are working in Stirling House, the luxury conference centre created out of the ramshackle shell of an officers' mess at the former RAF Stradishall bomber station.
Delegates stay in rooms cleaned by women prisoners who also serve them coffee, prepare their lunch buffets and set up the conference rooms.
Mr Wheatley said: "Prisoners not only work within the conference centre but were also instrumental in renovating the old building into a residential centre. The catering and conference management skills the prisoners are acquiring in the centre will stand them in good stead when they leave prison."
The conference centre was the idea of Highpoint's governor Roy Woolford, who has helped to rid the prison of a reputation for indiscipline and violence which inspired tabloid headlines like "Hi-de-Hi Point" and "Knifepoint".
He said: "The conference centre is a no-lose situation. The customers get a good deal because we are cheaper than other centres. The prisoners who built it and work in it get their qualifications. The RAF society has a redecorated officers' mess and Highpoint gets an income which saves money for the taxpayer."
Visitors can pay pounds 35 for bed and breakfast or pounds 80 a head for a conference package, which includes a four-course dinner offering dishes such as salmon steak Bearnaise and spinach and pine nut stir-fry. Mr Woolford has even procured house wines called Governor's Order, a Chilean white and Governor's Reserve, a red Merlot.
The centre, which opened in May by staging conferences for groups of Prison Service officials, is now ready to cater for outside organisations and is already fully booked for August and September. Clients include the Racal telecommunications company and Suffolk Probation Service.
The six prisoners who work at the centre are paid enhanced wages of pounds 15- a-week. Before delegates arrive they must prepare the beds and clean the en suite bathrooms in the 24 rooms, then help to facilitate the conference - returning to their cells before the bar opens in the evening.
One inmate Bella, 39, who is nearing the end of a sentence for manslaughter, said: "The atmosphere is totally different from the rest of the prison and it's good experience too. I'm hoping this work will get me a good reference so that I can get a job as a housekeeper."
Angie, 45, who is serving four years for drugs supply, said the success of the conference centre had acted as a beacon of hope for Highpoint's women prisoners. "When I tell new girls who are just beginning a long sentence what I am doing, it helps them to see that there is light at the end of the tunnel."Reuse content