I have been using Monzo to pay for all my expenses for a little less than two months; I have also recently moved to London and educated myself about the many idiocies related to KYC procedures and the obtuse reliance that banks have on credit scoring as a proof of address.
So the idea is very simple:
Provide paid for services to clients with a poor/non-existent credit score to:
A) Facilitate the opening of a Monzo bank account to expats who have recently moved to the UK
B) Help new clients build a credit history/improve credit score
The former could be achieved by requiring a simple “symbolic” one-off payment (e.g. £2-5) which would go - for instance - towards instantly reporting the creation of the account to CRAs and/or monthly updates.
The latter could be achieved by issuing a small loan (e.g. £120-240) backed by a security deposit to be segregated in a separate balance which will decrease every time an automated monthly repayment is made (I will be happy to discuss the missing details on how to implement this and other alternatives as well).
Also, I do not think that expats will need an overdraft facility you could easily profit from.
From a personal point of view I have been banking for 20+ years and I never had a negative balance with high street banks, all the expats I know have an excellent grip on their finances and have had the same experience as well.
It is also my understanding that about 40% of the locals regularly uses overdraft, so I guess it would be a matter of how Monzo is going to position in the market.
On a different note, I would also consider offering to both expats and non-expats the ability to personalise cards: a plain color for a low fixed fee (e.g. £1/£2) or custom graphics for a higher fee (e.g. £5/£10). For instance I love the coral card and yet, I would love to have a gunmetal black card.
If you want to go overkill, you may offer a black metal card for £25. Ideally something similar in design to the AMEX Centurion.