Placing a value on any business is always a notoriously tricky task. The ultimate barometer is what someone is willing to pay for it. In September, however, using a variety of metrics and different models, The Currency sought to ascribe a value to 50 of the largest privately owned businesses in the country. One of the most striking aspects of the list was the number of mechanical and engineering contractors in the list. Having ridden the boom in data centre construction across Europe, three such companies made their way into the top ten: Winthrop Engineering, Mercury Engineering and Jones Engineering.…