The Government is setting up a mechanism for sharing criminal records information with India (see below). While the UK has similar arrangements with some other countries, the detail has usually meant that information only gets exchanged when people are applying for immigration visas. However, the last quote (from The Sunday Times) suggests that India will have access to UK Warnings Index / ViSOR information (or more) if they are able to identify 'criminals' before they board the plane! As it says, there is still further negotiation about exactly what information will be shared, when and how, but you can see the direction of travel.
Government statement: The MOU on criminal records exchange will lead to British and Indian law enforcement bodies sharing criminal records information, fingerprints and intelligence. This will assist the police in protecting the public from known criminals, including sex offenders. It will also allow the courts in both countries to access more information to support tougher sentencing decisions. Details of the types of information exchanged through the MOUs and operational procedures, together with the details of any restrictions on using or disclosing the information will be the subject of further negotiations. However, the documents recognise the need to respect privacy, civil liberties and human rights.
From the Times: Officials believe it will make it easier to stop known criminals — particularly sex offenders — from getting on aircraft.