This sounds like a really intractable problem. In fact it is very easy to solve:
St Ann's Mill is now almost vacant, and in its present dilapidated condition is only worth about £75,000 because a commercial owner would have to invest heavily before seeing any return. The building is 175 years old, but it is built like a castle with 600mm walls and it won't fall down any time soon. The Council should make it available to the voluntary / charitable sector for use as a Community Punishment and Rehabilitation Centre, in partnership with the Probation / Prison Service and the Further Education sector on a 25 year full repairing lease. Current legislation requires the Council to charge an economic rent, but it can give an equal grant-in-aid, so that there would be no net cash transfer. The Council has no income from the building at present, so the transfer would be value neutral, but it would get the building refurbished as part of the deal.
The building would be used as training and rehabilitation centre for petty criminals engaged in the construction of the Kirkstall Valley Public Park. None of the the four partners could do this job on their own, but each would bring to the table one essential component that the others do not have. The Council has land and buildings, but little spare capital or revenue; the Probation / Prison Service has considerable "free" labour, but no land or money; the Further Education sector can provide vocational training and supervision, and recoup its costs, but it has no land; while the voluntary / charitable sector can engage with the local community and legally accept the free labour input, something that a local Council might find difficult to do. Charities can raise money and apply for grants that are closed to the other partners.
The economics of the scheme are transformed by the low labour costs. Constructing a new inner city public park is an ambitious target that is likely to take some time. Ten years might be a realistic estimate, but the delay doesn't greatly matter, because there will be steady progress and the outgoings are under control. This is all new work, that would not otherwise happen, so there will not be the job displacement issues that sometimes arise on community punishment schemes.
St Ann's Mill is almost ideally suited to this task. It is near the middle of the new park, it has a large garage for dumper trucks and a delivery yard for materials, and it can provide a refectory, training areas, washing facilties, toilets and some safe dry workspace indoors when outdoor working is not feasible. It would be refurbished as part of the scheme, and would eventually become a visitor / interpretation centre for the new park, and a base for Leeds Canoe Club to operate a new white water training coure on the River Aire. We think this is a more creative use for an historic building than trying to adapt it for high-tech uses it was never designed fulfil.
High tech incubator units are best located within the Council's Domestic Street complex, where refurbishment costs are low, and there is a large quantity of vacant space. These are secure, multi-storey buildings with a goods lift, concierge, and good access to the motorway network. The large square rooms will readily subdivide. DDA adaptations are straightforward and the costs are low.
Abbey Mill is not so difficult to repair. The surveyors' costs already include redecoration and long term maintenance, but the key activity is to mend the roof, stop the water penetration, and arrest any further decay. This work could be contained within the allocated revenue budget, which is also sufficient to fund essential fire precautions and basic health and safety work. Considerable costs can be avoided by leaving tenants in place. The building would at least be stable and functional and the options could then be reviewed.
Refurbishment costs at Abbey Mills could be reduced by a more sensible sub-division of the building. There is considerable duplication within the current estimates, but in most commercial operations the tenants are willing to share. In my view there is both a market and a continuing need for very low cost, very basic units, and this perhaps an area where the Council should be engaged. However, if it were decided that Kirkstall needs some business incubators, then the construction costs at Abbey Mills are comparable with those at St Ann's Mills. These could be established in the former "Chromogene" accommodation, leaving our other tenants where they are.
The advantage of leaving Abbey Mills in industrial use is that no new road access would be required. There is no need to cut down the trees in Abbey Villa, or to demolish the garden wall, or the listed Unit 2, and no need to create a fundamentally unsafe access onto a busy and congested arterial road. Vehicle speeds are low near the current entrance, which has operated without recorded accidents for over 200 years. It could, if necessary, be widened with less total environmental damage than the proposed route through Abbey Villa. A left in - left out arrangement should be encouraged, and perhaps enforced by a new traffic island in the middle of the A65 Abbey Road, opposite the entrance. It is not difficult to drive out in a vehicle, simply by waiting for a red traffic signal on the A65.
There is an issue about units 5 and 6. These are currently vacant and semi-derelict, but are among the oldest and most historically interesting parts of the mill. There has not yet been a proper survey, so we do not really know the scale of any problems. Plainly it needs a new roof! Instead of leaping into a decision that residential conversion is the only way forward, no great evil will result from making a detailed survey of this building, to gain a better idea of the issues and the likely costs.
This site is still under construction. I am working as fast as I can!