Tata Consultancy Services (TCS) has secured a long-term contract worth more than $1 billion from Telefónica UK, marking its first mega deal in nearly two years, Mint reported. The agreement, spread over a decade, is expected to generate over $100 million in annual revenue and brings relief to India's largest IT services firm after a prolonged slowdown in winning large-ticket contracts. Telefónica UK, the British subsidiary of Spanish telecom major Telefónica, operates the O2 mobile brand. Under the deal, Mumbai-headquartered TCS will deliver application management and infrastructure services, with a significant portion classified as new work for the company, executives familiar with the matter told Mint. An official announcement is likely in the coming weeks.