ONE of Southampton's biggest employers is set for a dramatic office shake-up within the next three years, the Daily Echo can reveal.

Ordnance Survey, the national mapping agency that underpins £1 billion of economic activity in the UK and employs more than 1,200 people at its headquarters here, is narrowing down its search for a new home.

But bosses have vowed to stay in or around Southampton.

As previously reported, the historic organisation needs to move out of the sprawling 22-acre site at Romsey Road, Maybush, where declining staff numbers have left empty offices, making it too expensive to maintain.

It is understood two options are now being looked at closely by OS, which has just recorded a £5.6m profit on a £116.3m turnover for the year.

They are either to demolish the current 35-year-old HQ, so a modern building can go up there, or to construct a purpose-built head office within five miles of the current location on a site yet to be decided.

Either move would spark a scramble for the contract in the construction industry. OS spokesman Scott Sinclair said: "The scale of the project is such that staff are not expected to move into a new building - whether on the existing or a new site - until 2007. Whatever the outcome, Ordnance Survey said its intention would be to remain in or close to Southampton."

Bosses are also considering relocating the Romsey Road printing and warehousing facilities to an as yet undecided industrial site. Staff are being briefed on the latest developments, and advertisements are about to appear seeking specialist companies to assist in the relocation task.

Discussions have now begun with the city council about possible alternative sites locally, along with planning permission and related issues.

A council spokesman said: "The council has been talking to OS for some time and it is delighted that this historic organisation is keen to stay in the city. Clearly times change, and the current site is too large, but we've already begun work with the agency to find alternatives to ensure their continued prosperity."

OS, headed by £170,000-a-year Vanessa Lawrence, is also in talks with other district councils responsible for planning issues all within five miles of its existing site.