The main reason that more are looking to specialist currency brokers to manage their currency transfers is that they can get access to better exchange rates.
..brokers stand out because “you’re unlikely to receive the same personal services at your high-street bank as you would from a foreign-exchange dealer who is familiar with your requirements and would be your point of contact on an ongoing basis if you made regular payments.”
For example, a priority payment with Barclays costs £40 and takes one to three days. Standard payment costs with Barclays are £25 and take three to five days. By using a currency broker, the transfers will in most cases be free and transferred either the same day or within one to two working days, depending on where you’re sending the money.
(quotes from The Telegraph)