House prices in 'AL9 7', Welham Green

Defining 'AL9 7'

This analysis is limited to properties whose postcode starts with "AL9 7", this is also called the postcode sector. There are no official postcode sector names so I've just labelled it AL9 7, Welham Green. It is shown in red on the map below.

Want to change geography?

You can click on the map above to change to a neighbouring sector, or you can use the search form below.

Distribution of £ per sqft for 'AL9 7' vs 'AL9'

The chart above is called a histogram, it helps you see the distribution of house price per sqft in AL9 7 To make this chart we put all the sales data into a series of £ per sqft 'buckets' (e.g. £580 to £603, £603 to £627, £627 to £650 etc...) we then count the number of sales with within in each bucket and plot the results. The histogram is based on 117 sales that took place in AL9 7, Welham Green, Brookmans Park in the last 24 months.

Generate a custom histogram like the one above but based on your own criteria.

You can see the spread of prices above. This is because although internal area is a key factor in determining valuation, it is not the only factor. Many factors other than size affect desirability; these factors could be condition, aspect, garden size, negotiating power of the vendor etc.

The spread of prices will give you a feel of the typical range to expect in AL9 7, Welham Green. Notably, only 25% of properties that sold recently were valued at more than £654 sqft. For anything to be valued more than this means it has to be more desireable than the clear majority of AL9 7 homes.

Box plot of £ per sqft for AL9 7

Tip: click on the chart to see the values.

The chart above is called a boxplot (or a box-and-whisker plot). Box plots, like histograms, are used to graphically represent the distribution of data, showing the central tendency, spread of the distribution. In the context of £ per square foot property price distributions, box plots represent the variation in property prices within a geographic area e.g. Welham Green. The chart above shows a boxplot for 'AL9 7' as well as the 'AL9' postcode district.

Property price map for Welham Green

Have a look at the interactive price map I created for myself. Use it to explore 'AL9 7' house prices all the way down to individual property plots.

House price map for Welham Green

Welham Green house price forecasting

I cannot tell what house prices will do in the future and don't believe anyone who says they can. However we can plot price trends, I have done this in the chart below for AL9 7 (Welham Green) compared with the wider postcode district of AL9. You can extrapolate from this based on your own views on future interest rates, inflation and other factors.

House price index for AL9 7

Tip: click on the legend items to show/hide different lines

Download house price index as CSV (premium users only).

The chart above shows changes in 'AL9 7' property prices over the last 20 years. The index is calculated from the average price paid per sqft for property in AL9 7 and is set to 100 in 2004. I'm comparing the trends for AL9 7,Welham Green with the wider postcode district of AL9 What is more interesting is to look at the difference between flats and houses, even those in the same area follow a very different trend, to get a robust enough sample size to see this we need to zoom out and look at house price trends for the entire Welwyn Hatfield local authority.

The dashed lines show nominal house price changes, the solid lines show the same data adjusted for inflation. Economists call this the 'real' price change. You have to take inflation into account when comparing prices over time. It's calculated using the formula:

Real Rate of Return = (1 + Nominal Rate) ÷ (1 + Inflation Rate) – 1

Historic returns for AL9 7

This table complements the house price index chart above, presenting the data in a more detailed format. It breaks down the information into 20-year, 10-year, 5-year, and 1-year periods, further categorized by property type. For each period, we display both a per annum rate of change and a total rate of change.

The total rate of change represents the overall change over the entire period. The formula for total return is:

Total return = (Index at end of period ÷ Index at start of period) - 1

The per annum rate of change is the annualized rate of change over the period. This is equivalent to the annual bank savings rate you would need to achieve the same total return over the given period. This annualized return is also known as the Compound Annual Growth Rate (CAGR). The formula for CAGR is:

CAGR = (1 + Total return) ^ (1 ÷ Number of years) - 1

Some specific examples:

• Over the past 20 years, AL9 7 sector have seen a 0.7% annual change when adjusted for inflation. This translates to a total change of 15.6% in real terms.
• Over the past 5 years, AL9 7 sector have seen a -2.4% annual change when adjusted for inflation. This translates to a total change of -11.4% in real terms.

Most recent AL9 7 sales

For the most recent sales activity, rather than a summarized average, it is better to see the underlying data. This is shown in the chart below, where blue dots represent individual sales, click on them to see details. If there is an obvious trend you should be able to spot it here amid the noise from outliers.

Tip: hover over dots to see details

Nearby geographies

The table below shows how 'AL9 7' compares to the other postcode sectors in AL9.

Raw data

Our analysis of AL9 7 is derived from what is essentially a big table of sold prices from Land Registry with added property size information. Below are three rows from this table to give you an idea.

See the entire list of all sales in AL9 7 here.