If you ask the bosses at Tata Sons what big shifts in group strategy they made last year, they will tell you: None – it was just that the world started to sit up and take notice.

More than any other deal, it was Tata Steel’s launch of its ongoing £5.5bn bid for Corus of the UK that put India’s global ambitions, and those of the Tata group, India’s largest private-sector conglomerate, on the map in 2006.

Tata officials say the move, the largest Indian attempt to buy a foreign company, is only an extension, albeit a very significant one, of an internationalisation strategy introduced by the group’s chairman Ratan Tata several years ago.

“The Corus offer demonstrates a willingness to do larger things, raise finances and be bolder than we might have been previously,” says Alan Rosling, executive director at Tata Sons, the group’s parent company.

For the outsider, the historic group is bewildering in its size and complexity, with 430 corporate entities and 90 operating companies. But three businesses account for 60 per cent of the group’s $21.9bn in sales and 83 per cent of its profits – Tata Steel, Tata Consultancy Services (TCS), the information technology outsourcing unit, and Tata Motors, maker of trucks and cars.

Founded by Jamsetji Tata in the mid-19th century, the group is controlled by three trusts and employs a quarter of a million people across sectors that also include chemicals, engineering, telecoms, energy and consumer products.

Last year marked a step change in Tata’s overseas forays. Tata Tea, the group’s beverage outfit that bought Britain’s Tetley for £271m in a then landmark transaction for India in 2000, was particularly busy. The company paid $677m for a 30 per cent stake in Energy Drinks of the US, $220m for Eight O’Clock Coffee, also of the US, and bought 33 per cent of Joekels Tea Packers of South Africa.

The group’s Indian Hotels unit bought the Ritz Carlton Boston for $170m and TCS bought a small company in Australia.

The group also worked on consolidating acquisitions from previous years, such as Singapore’s Natsteel, which Tata Steel paid $485m for in 2004, and Thailand’s Millennium Steel, which it bought for $404m in 2005.

With these acquisitions, the share of international revenue in the group’s turnover has risen rapidly, from $2.6bn or 21 per cent of group sales in the year ending March 2003 to $6.7bn, or 30 per cent in the year to March last year.

TCS remains the greatest earner of foreign exchange, accounting for 36 per cent of international revenue last year with its vast outsourcing contracts in developed markets, followed by Tata Steel, with 22 per cent. But Tata Motors, for instance, is making inroads into markets such as South Africa.

If Tata Steel’s bid for Corus is successful, it will change the whole tilt of the group. Corus has revenue of about $20bn, which would mean for the first time more of Tata’s turnover would be from overseas. It would also mean that most of the turnover would be in one industry, steel.

Tata says it needs to internationalise to capture growth, build scale, diversify its commercial and political risk, gain access to strategic assets and technology and to secure natural resources.

Mr Rosling says the common thread linking the international strategies of the group’s various units is a business model that aims to be “geographically neutral”. In practice, this means finding the best skills and raw materials at the lowest costs wherever they occur in the world.

For example, Tata Steel, one of the world’s lowest-cost producers of the commodity, will ship raw steel for finishing at Corus’ sophisticated but high-cost plants in Europe. Tata Steel gets a new market for its production while Corus gets low-cost inputs.

Another example is Tata Motors’ research and development centre in the UK’s Midlands, taking advantage of experts in that region to help design its products for home.

Some of the Tata Group’s strengths, however, are also its weaknesses. Its chairman Ratan Tata is the principal proponent of its internationalisation and is as often to be found outside India as inside the country.

But as Mr Tata approaches his 70s he has no obvious successor, particularly within his own family. This could result in the group losing focus and influence within India, whose corporate culture favours dynastic leaders, once he steps down.

“I wonder whether the Tata magic does become affected if you don’t have a Tata at the helm,” says one banker in Mumbai.

The other big question for Tata Sons will be how to rebalance its portfolio. A large part of its estimated $50bn holdings is locked up in TCS. This will need to be redeployed to other parts of the group, but the question is to where and for what.

“Will Tata Motors buy an overseas brand that might be being sold by a Ford, GM or a Chrysler. Or will TCS go and buy a major European IT services company?” says the banker. “Those are the sort of questions people will be asking about Tata.”