British Prime Minister David Cameron arrived in India on Monday with what he called Britain's biggest ever overseas business delegation for a three-day visit clouded by a corruption scandal.
After an investigation in Italy suggested kickbacks were paid via middlemen to secure the deal, India has taken steps to cancel the contract and started its own police investigation.
The British prime minister is likely to face further questions about the probe -- the helicopters, for use by VIPs, are being manufactured in southwest Britain -- with the Indian government keen to be seen to be acting tough on its latest problems.
It has taken the gloss off Cameron's second trip to India since being elected in 2010. He arrived pressing for deeper economic ties between the two countries which are united by their colonial history.
"I've brought with me the biggest ever business delegation to leave Britain shores and I'm really proud to be bringing them here, to meet with Indian businesses and to link up our countries," he said on Monday.
Speaking at a factory of partly-British consumer products group Hindustan Unilever, he said that "India's rise is going to be one of the great phenomena of this century" and that "Britain wants to be your partner of choice".
The British leader has targeted a doubling of annual bilateral trade from 11.5 billion pounds ($17.8 billion, 13.4 billion euros) in 2010 to 23 billion pounds by the time he faces re-election in 2015.
Among his delegation are executives eyeing moves by the Indian government to open up the retail, airline, banking and insurance sectors to foreign investors.
It also includes heads of six British universities aiming to attract students to Britain and seek partnerships in India's vast higher education market.
After business meetings in Mumbai on Monday, Cameron will fly to New Delhi for talks with Prime Minister Manmohan Singh and President Pranab Mukherjee on Tuesday.
His pitch to New Delhi echoes similar statements from fellow Western leaders seeking to hitch their stagnant economies to one of the most dynamic regions in the world.
India's economy has slowed sharply, but is still growing at about six percent annually.
The timing of the helicopter corruption scandal could therefore not have come at a worse time as Cameron seeks greater market access for British companies and more trade.
He was also expected to remind the Indian government of the merits of the part-British Eurofighter jet, which was competing for a $12 billion contract until last year.
India chose France's Dassault Aviation for exclusive negotiations but the deal has still not been signed.
Indian investigators will travel to Italy as early as this week as part of an inquiry into the alleged kickbacks, a spokesperson for the Delhi-based Central Bureau of Investigation said Sunday.
On his last trip to India in 2010, Cameron issued an unexpectedly blunt warning to India's arch-rival Pakistan about promoting "the export of terror", which played well in New Delhi but provoked a furious response in Islamabad.
Pakistan's ambassador to Britain accused Cameron of "damaging the prospects of regional peace".
As well as trade, Cameron will use the trip to correct any misunderstandings about his government's drive to slash immigration numbers amid concerns that young Indians could be deterred from applying to study in Britain.
"There is no limit on the number of students who can come from India to study at British universities," he told the Hindustan Times in an interview.