In response to a question about the role London plays in the global creative industry, Grant told the committee the UK capital was a "hub" for the FMCG giant – but that this relied on the wide pool of talent available.
"We see the UK as a centre for creative excellence that sits alongside New York," she said.
"It has a real diversity of talent, and we have created some fantastic ad campaigns that have gone on to be well known around the world.
"So it’s really going to be critical to be able to maintain the access to that talent, both at a creative level and a tech and data level."
The availability of talent has remained a concern for the creative industries since the UK voted to leave the European Union last June – a decision intertwined with moves to control immigration.
Smith, meanwhile, said that Isba feared loss of influence for the UK when it came to the development of future regulations around data – though he acknowledged that the government took the need for regulatory equivalent "very seriously".
"We welcome the bringing of GDPR [General Data Protection Regulation] into a UK context and we know our own Information Commissioner’s Office has been a strong force in helping to formulate that," he said.
"Where we have more concern is when it comes to future regulations and the direction of travel of EU regulations in data protection, relative to that we might fight for if we were on the inside. We already see a loss of influence in the steering of the e-privacy directive, for example."