The firm said the closures formed part of a series of carefully planned structural changes within the organisation, designed to drive improved business performance.

Problem contracts at both offices were blamed for losses in the South West division last year.

The group’s Cardiff office, which is part of the second biggest of four regional arms, suffered a disappointing performance due to a challenging student accommodation project.

Central & West divisional revenues for 2015 were also affected by the same principal contractor withdrawing from a secured project where T Clarke was also its partner.

In a trading statement the firm said: “Having reviewed the opportunities for our Bristol and Cardiff offices, we have concluded that they are not capable of delivering the quality of opportunity or level of sustainable margins that we require and therefore both will be closed by the end of 2015.

“The activity of these offices will be reported as a discontinued operation and is expected to incur a pre-tax loss of £2.6m including cash closure costs of £0.3m.

“All outstanding contractual obligations will be assumed by an expanded TClarke South West.”

The decision leaves just Plymouth and St Austell offices covering the south west and Wales.

Across the rest of the business now strongly focused on the south east and north, T Clarke said it had seen a steady improvement in orders, running 15% ahead of last year at around £320m.

Of the current forward order book, £190m represents work secured for 2016 and £50m for 2017 and beyond.

T Clarke said that the decision to stick with quality main contractors and bid only on those contracts that offer appropriate returns, particularly on London work, would deliver a significant rise in operating margin during 2016 and 2017.

In London work has just started or is due to start on major projects at Angel Court, Mizuho Bank, Principal Place, Rathbone Square, and London Wall Place.

Net debt reduced from £8.7m at the half year to £6m at the end of October.