In times of economic uncertainty, paying down debt is a sensible course of action.
Of course you shouldn't make an overpayment until you have adequate savings built up to cover exigencies such as illness, temporary periods of unemployment, repairs and replacement of consumer durables etc..
With the increased risk of redundancy and diminished re-employment prospects the standard of a rapidly accessible rainy-day fund of 3 months average expenditure may be insufficient for most people.
However, the majority of people will be well advised to look at reducing all their debts (starting with the highest rate shortest-term ones) and mortgage debt is a part of this.
This advice is especially relevant to those whose mortgage terms stretch into their anticipated retirement years - with declining pension yields such commitments may be unsustainable at that stage in their lives.