Last week I was wondering what was happening with MasterMap and the Geospatial Commission. Today somewhat to my surprise the Government announced a plan for opening up (some) OS MasterMap data.

The important points are in the Cabinet Office narrative with some additional detail in Ordnance Survey's FAQ. There are also press releases from Cabinet Office and from Ordnance Survey.

ODI has posted a good overview and there's a slightly nonplussed response from the AGI.

Below are a few observations from me.

Contrary to some of the more excited reactions, Ordnance Survey has not announced that MasterMap or the Topography Layer will be released under the Open Government Licence. The open data commitments in the announcement are limited.

However they are significant. One of the potential interpretations of the November budget statement was that Government would try to avoid a proper open data release and just provide some "free" MasterMap data to small businesses. There is more to the plan than that.

So today's announcement isn't the worst case scenario. It's more like another one of those ambiguous "This is a good start ..." scenarios that the open data community has grown used to.

What's the substance of the announcement, based on the narrative?

First the open data:

The datasets available under the OGL are:

  • Property extents created from OS MasterMap Topography Layer; and
  • OSMM Topography Layer TOIDs (TOpographic IDentifiers) will be incorporated into the features in OS OpenMap-Local.


The tense is a bit odd. We don't have a firm commitment on the timing: OS's FAQ says "The implementation project is expected to last 24 months with deliverables during this period." However presumably the open data could be delivered more quickly than the other measures.

(An aside: 24 months takes us to 2020. The "CLG contract", under which the original arrangements for OS OpenData were agreed, expires in 2020.)

Note that property extents are not the same as building polygons. Those two subsets of the Topography Layer have overlapping but distinct uses, so under this plan the door is still closed to a lot of potential for open innovation.

[Edit: subject to clarification. "Property extents" aren't actually a feature in the Topography Layer, and Topo doesn't show information on land and property ownership. But we know Land Registry's polygons are derived from OS data.]

I'm not entirely sure whether OS is talking about releasing a new data product containing the property extents data from MasterMap, or simply allowing existing MasterMap licensees to release property extents derived from MasterMap.

The latter approach would allow Land Registry to release their National Polygon dataset as open data without the existing derived data issues – if they wanted to – and would similarly make it easier for councils to publish planning data. However that wouldn't get us a full national dataset of property extents. I hope the intention is for OS to publish the bulk data directly.

The TOIDs are mainly about linking to data from other sources. Useful, but OS OpenMap-Local doesn't have the full detail of Topography Layer so this won't be the full set of TOIDs.

Then the free data:

The datasets that will be made available for free up to a threshold of transactions through the APIs are:

  • OS MasterMap Topography Layer, including building heights and functional sites;
  • OS MasterMap Greenspace Layer;
  • OS MasterMap Highways Network;
  • OS MasterMap Water Network Layer; and
  • OS Detailed Path Network.


Note exclusion of the Imagery Layer and the Integrated Transport Network Layer.

Free is free of charge, but not open. It's difficult to judge the impact of this move as we don't yet know what the cap (threshold of transactions) will be, whether that cap will depend on intended use and/or the category of user, and (crucially) what the terms of re-use will be for data extracted from the APIs.

OS's FAQ says rather gnomically: "The transaction threshold will be comparable to that increasingly available for similar APIs. This will be designed during the implementation phase, in consultation with the sector." (What sector is that?)

There are a lot of considerations. How disruptive will these free APIs be (or how disruptive does Government want them to be) to existing value-added resellers such as Promap? Could OS leverage the free APIs to upsell its commercial services, and if so will that create competition issues?

Also:

New guidance will be released on using derived data from OS MasterMap, including supporting local authorities to understand how to publish more derived data as open data.


This resonates with some work Ben Proctor started at Open Data Camp 5 in Belfast, on clearer guidance for the "presumption to publish process" in the Public Sector Mapping Agreement. This process is under-used, partly because it's difficult to understand, so any clarification will be welcome. However derived data will persist as a serous barrier until OS releases more of MasterMap as open data.

And this:

Furthermore, over the next 12 months the Geospatial Commission will work with GeoPlace, the LGA, the Improvement Service (on behalf of Scottish Local Government), and OS to investigate opening up the key identifiers UPRN and USRN, together with their respective geometries, for the whole of Great Britain under OGL terms. This work must protect the integrity and authority of these identifiers, so as to provide both businesses and public sector organisations with the confidence to continue to rely on these within their own products and services, without restricting their ability to use and benefit from them.


Not a commitment, only a further negotiation. More identifiers. But note: "with their respective geometries". Geometries is points, line and polygons. UPRN/USRN with geometries is substantially more of the Topography Layer than today's commitments. And UPRNs go beyond the Topography Layer – they are allocated to address points in AddressBase, Ordnance Survey's geocoded national address dataset.

I think there are two ways we can look at today's announcement.

The intention was that the Geospatial Commission would oversee negotiation of the future of MasterMap. However the Geospatial Commission has been delayed, and the Government was under pressure to announce something.

The cynical view is that Ordnance Survey has seized this opportunity to steer the course of future geospatial strategy before the commissioners are in place, by outwitting Cabinet Office civil servants and descoping ambitions for a wider open release of MasterMap.

The more optimistic view is simply that the timescale has been adjusted – today's announcement can be seen as a set of interim measures, with the main negotiation for opening MasterMap (and possibly also open address data) still to take place over the next 12 months under the oversight of the Geospatial Commission.

Cabinet Office estimates that the MasterMap measures announced today: "will boost the UK economy by at least £130m each year …" The Geospatial Commission announcement in November talked about "helping to grow the UK's digital economy by an estimated £11bn each year". So we have reason to expect that there are more substantial changes in the pipeline for UK geospatial data.