DR Mante Nieuwland and his wife Andrea, who both lecture in psychology at Edinburgh University, came to the capital from Spain two years ago, in good time for the arrival of Siardus, who is now eight months old.

They have opened a fixed rate Isa, a regular savings account and a junior Isa, all with ethical bank Triodos.

"Big banks can use your money for whatever purposes they want and you would not have any idea," Dr Nieuwland said. "I like it that it is ethical and it also seems more transparent, with information readily available." The couple still have a current account with HSBC, but say they are waiting for Triodos to launch its current account in the near future.

The Triodos online cash Isa pays 1.4 per cent but is not instant access, requiring 33 days' notice of withdrawals. Its Junior Isa pays 2 per cent.

Savers could opt for the Charity Bank's Ethical Isa, offering 1.5 per cent also with a 33-day notice period. Scottish adviser Virtuo Wealth also runs its own charity Isa.