In a Mayfair wealth firm, the friction is rarely about advice quality. It is the hours lost moving client data by hand between platforms that should already be passing it to each other. That is what brings advisers, IFA principals and family-office COOs here looking for custom software. Mayfair and St James’s hold the densest concentration of advice-led wealth in the country, from St. James’s Place (the FTSE 100 firm whose funds under management reached a record £220bn at the end of 2025) to the single- and multi-family offices clustered across St James’s Square. The operations behind that address are recurring and exacting: client reporting, ongoing suitability, multi-custodian consolidation and compliance. The off-the-shelf platform running them was never built to do the one join you now need. This page is about the software work that sits around that platform.
The Adviser and Reporting Platforms in Use Here
Firms here are rarely starting from a blank page. Most advice businesses run their back office on Intelliflo Intelligent Office (the dominant UK adviser practice-management system, used by roughly a third of UK advisers) or on Iress Xplan, the main alternative, built around integrated CRM, advice and compliance workflows. Portfolio reporting and aggregation sit on platforms like SS&C Black Diamond, Avaloq, or, for family offices wrestling with multiple custodians, the London-built Landytech Sesame. Accounting typically lives in Xero or Sage.
Replacing any of these is almost never the right call, and we do not propose it. A firm that has standardised on Intelligent Office has years of client history and process built on top of it; the value is in keeping that system as the source of record and building the connections it does not provide. The development work belongs at the seams: where one platform’s output has to become another platform’s input, and a person is currently doing that translation.
Where the Multi-Custodian Picture Falls Apart
Rarely is any single system the culprit. It is that several capable platforms sit beside each other without lining up, so the work of reconciling them lands on staff:
- The adviser back office (Intelliflo or Xplan) does not feed the portfolio and reporting tool cleanly, so valuations and performance get reconciled by hand before a review.
- It does not feed the accounting platform either, so fee revenue and invoicing are rekeyed into Xero or Sage every month.
- Custodian feeds, the CRM and document storage each sit in their own silo, and someone stitches them together manually ahead of every client meeting.
- For a family office, consolidating positions across multiple custodians, banks and private assets is a slow monthly Excel exercise. Landytech built Sesame to absorb exactly that, connecting to 500-plus custodians and data providers.
These seams are not edge cases; they are the firm’s monthly rhythm, and each one is a standing manual task that scales with the client book. Custom API integration replaces that rhythm with data that moves on its own. SS&C Black Diamond, for instance, exposes real-time and JSON batch APIs for positions, transactions and cost basis: a clean target that turns a weekly export-and-reconcile ritual into a feed the team never touches.
Consumer Duty Turned Suitability Into a Live Data Problem
Since FCA Consumer Duty landed, ongoing suitability has stopped being an annual tick-box and become a continuous reporting obligation. The stock platform reports it poorly. The FCA’s February 2025 review of the largest advice firms found suitability reviews were delivered in around 83% of cases, and explicitly flagged “insufficient management information to allow senior management adequate oversight.” For a Mayfair principal, that translates directly into a data problem: which reviews are due, which were delivered, and which clients are drifting out of contract, all visible on demand.
Bespoke development helps here. The systems we build pull review status, fee-versus-service data and the underlying MI out of separate logins and into a single reporting layer, so a principal can see, at a glance, which reviews are due, which were delivered, and which clients are drifting out of contract. The platform you already own holds most of the data. A consolidated, always-current view across it is what gets built.
On-Brand Portals for High-Value Client Relationships
For a Mayfair firm, the client experience is part of the proposition. A high- or ultra-high-net-worth client paying a premium expects reporting and document access that feels as considered as the relationship. A generic, off-brand platform portal undercuts that. Established boutiques here run exactly this kind of relationship at scale: Raymond James operates from 1 Mayfair Place, and Killik & Co has its head office at 46 Grosvenor Street, both serving large books of private clients whose expectations a stock portal rarely meets.
The work here is a bespoke, on-brand client or investor portal: a single-page web app built on the platform’s API that carries the firm’s identity, with secure document delivery and consolidated reporting behind it, while the system of record stays where it is. The off-the-shelf product cannot give you that front end; the real data flows into it automatically rather than being uploaded by an administrator each quarter.
The work worth doing here is the recurring, operational kind: the integrations, reporting and portals a firm runs on for years. Most of these relationships continue well past the first project.
Working in Mayfair or St James’s?
If valuations, fee data and the suitability picture only come together when someone spends a day in spreadsheets, and Consumer Duty has made that an every-month demand rather than an annual one, that is a data-flow problem with a clear fix. Show us the report your team builds by hand each month, and we will tell you what it would take to make it build itself. Mayfair wealth management sits within our wider London work.
