Foundations
Part of Connected TV advertising in England: a maturing market or a passing fad?
How to build an England connected TV advertising market size estimate: method and worked example
No official series breaks out connected TV adspend for England. This explains what published UK sources measure and how to build an England estimate from a UK total.
Define the boundary before choosing a number
Weak version: Start with a UK total and label it an England market size. That shortcut hides the main limitation: no regulator, trade body or government department publishes a connected TV advertising total for England under that name.
An England number must be derived, so its boundary and method need to be stated rather than implied.
Better version: Describe the result as an estimate built from a named UK series, an England allocation and a fixed definition of connected TV advertising. Keep the source period beside the number. That makes clear which parts were published and which parts came from your own calculation or judgement.
Give each source a separate task
Weak version: Combine viewing, investment and digital advertising figures as if they measured the same thing. They do not. Viewing estimates describe audiences, while expenditure reports describe spend; neither becomes an England figure simply because it relates to television or online video.
Better version: Match the source to the input it can support. Barb supplies UK viewing estimates, Thinkbox covers BVOD definitions, buying routes and investment reporting, and the AA/Warc and IAB UK/PwC studies provide UK spend series for different advertising categories.
| Source | Published measure | England split |
|---|---|---|
| Barb | Daily UK viewing estimates from panel, router and device data | No |
| Thinkbox | BVOD definitions, buying routes and investment reporting | No |
| AA/Warc Expenditure Report | Quarterly UK adspend by medium | No |
| IAB UK and PwC | UK digital adspend by format, including video | No |
Barb explains how total viewing is measured, which helps clarify the viewing input, not the value of the advertising. ONS statistics on the digital economy describe internet and IT businesses that support delivery and measurement infrastructure; they are not an advertising-spend series.
Use population as a starting allocation only
Weak version: Apply a population percentage and present the result as the observed England share of spend. A population-based calculation is a first pass, not a regional sales report, and it cannot account by itself for differences in viewing patterns or where advertisers concentrate their budgets.
Better version: Use about 84% as an initial allocation, based on England’s share of the UK population; the audience research guide covers audience inputs. The ONS annual mid-year population estimates provide the population context, not an observed adspend split. Television viewing skews older, and advertiser demand is concentrated in London and the South East. Track demand signals in England, including advertiser counts and upfront commitments, as indicators that may move before spend totals.
Decide which streamed inventory belongs in scope
Weak version: Use one label for every ad viewed on a television set. Some reports include user-generated video watched on a TV, while others count only broadcaster-owned streaming inventory. Regional estimates can also reflect agency or sales-house geographies rather than a single consistent England boundary.
Better version: Write down whether the estimate covers BVOD alone or every streamed ad served to a TV set. Keep the buying route visible too: BVOD is usually bought by television teams, while programmatic CTV sits with digital teams. Different scope choices can produce totals that look inconsistent even when each publisher has applied its own definition consistently.
Turn the inputs into a reproducible calculation
Weak version: Quote a headline without keeping the underlying inputs. That leaves readers unable to check the UK base, the period, the England share or any adjustment for regional buying. It also makes a later comparison unreliable if the source definition has changed.
Better version: Keep the arithmetic visible and mark illustrative values as placeholders. The example below uses illustrative inputs only; replace them with current, sourced figures before quoting an estimate.
| Input | Illustrative value | Source or treatment |
|---|---|---|
| UK CTV and BVOD ad spend | £1,000m | Chosen UK total, such as AA/Warc or Thinkbox |
| England population share | 84% | ONS mid-year population estimates |
| Population-weighted England total | £840m | Calculated from the two inputs above |
| Adjustment for London-weighted buying | Minus 5% to 15% | Judgement, recorded separately |
- Select one UK total and record its publisher and coverage period.
- Fix the inventory definition, such as BVOD only or all streamed ads served to a TV set.
- Apply the England share and state why that percentage was chosen.
- Record any adjustment for buying skew and the gap between rate cards and paid prices.
- Date the estimate and rebuild it each quarter using the same definition.
Treat the buying adjustment as a sensitivity range, not as evidence. Run the calculation three times on the illustrative inputs: with no adjustment the England total is £840m, with a 5% reduction it is £798m, and with a 15% reduction it is £714m. Quote the range and say the adjustment is a recorded judgement. If you cannot source a reason for it, drop it and quote the unadjusted figure.
The £1,000m input is a placeholder. For a real estimate, take the UK figure from the AA/Warc Expenditure Report or from Thinkbox's BVOD investment reporting, and write down the publisher, the coverage period and whether the figure is BVOD only or all streamed ads served to a TV set.
Keep audience measurement separate from ad pricing
Weak version: Treat measured viewing as an advertising market value. Viewing data can help describe exposure, but a market estimate also requires priced impressions and a stated basis for assigning those impressions to England.
Better version: Keep the stages distinct: viewing is measured, inventory is defined, and impressions are priced before an England estimate is assembled. The flow below shows why a viewing total cannot be read directly as spend. For evidence about what a campaign can demonstrate, choose connected TV advertising attribution methods; for reporting arrangements, plan measurement and reporting before launch.
Building an England CTV estimate
- Barb measures total viewing minutes
- Convert minutes into ad impressions
- Apply streaming inventory prices
- Check demand signals
- Publish estimate with inputs
Place BVOD in the trading picture
Weak version: Assume BVOD sits in the same reporting column as every other form of digital video. It is the best-defined slice, but it is normally traded within television budgets rather than digital display, so the reporting category may not match a device-based definition.
Better version: State both how the inventory is classified and how it is bought. Thinkbox's introduction to BVOD sets out its buying, measurement and reporting context. For the trading structure behind an England estimate, use the England market guide alongside your chosen scope, rather than assuming that one market label settles the classification.
Refresh the estimate without moving the yardstick
Weak version: Read every change between periods as a change in advertiser demand. New ad-funded streaming services, refreshed measurement panels and revised reporting definitions can all move a published total, even when advertiser demand itself has not changed.
Better version: Hold the inventory definition stable, date each input and note revisions to the source series. A defensible planning number has a named UK base, a documented England share and a clear period. If the estimate changes, show whether the cause was new demand, a changed source, or a different calculation choice.
