David, Wiltshire like many other brigades have a planned replacement programme for appliances, it is factored into the budget to replace appliances after say 15 years. The dennis appliances that Wiltshire run were first bought in 1995 and are likely to be amongst the next batch to be replaced after all the Mercedes pumps that Wiltshire use are replaced. Indeed many other brigades keep appliances longer than others, currently in some places pumps that are approaching 20 years old are still in use. This of course excludes specials as they are expected to have a longer life than that of a pumping appliance as they are used less and will generally be kept for say maybe 20 years or in the case of Leictershire, 27 years.
Added by Scally on 11 December 2008.