Jonathan's assignment is to investigate the building itself; looking for the architectural features that reveal how and why each building has changed over time and how it fits into the context of the local community.

In each programme our duo are called in to solve the hidden history of a house, no matter how big or small, old or new.

Dr Nick Barratt is our archive specialist. Dr Jonathan Foyle is our architectural historian and archaeologist.

The owner, Jakob Hartman inherited the deeds to the house when he bought it. With these came some intriguing documents going right back to the 1880s, including birth, marriage and death certificates belonging to previous owners  and  a letter referring to a blocked up doorway between his house and the one next door. But now, curiously, there's not a scrap of physical evidence to suggest that the doorway exists.

Jakob asks the Hidden House History team to find out when and how his house was first built and what the relationship is with the house next door. He's also keen to find this blocked up doorway.

Maps in the local archives reveal how Walthamstow has gone from a Victorian farming community to a haven for the commuter belt, with prices that reflect this. In 1884 the house was sold for £255, in 1994 it was £25,000 and now - who knows?

Spotting a change in the skirting board, Jonathan's initial investigation reveals that the bathroom is a later addition on top of the kitchen. The first floor bedroom has a handsome fireplace, the marble used shows the Victorian love affair with Italy, but the small grate inside is a reflection of the steamer ships bringing coal from Newcastle into London - no longer did you need a big basket for huge logs - just a tiny basket for a coal fire.

Jonathan's exploration moves upstairs, revealing how in a Victorian villa everything diminishes the higher up you go - rooms and windows get smaller and ceilings get lower.

Measuring up the house, Jonathan discovers that there's a proportional system through the house - the measurement of 2' 7" carries through doorways, halls and stair case. The Victorian builders must have thought this was ideal for the human frame. As he starts to draw up the plans he confirms his theory that the bathroom was a later addition. This does not fit with the idea that the house would have been built in the 1880s.

Jonathan consults a series of texts on toilet history he discovers that the vogue for having your own loo at home increased after the Great Exhibition. In 1861, Thomas Crapper produced his loo with a new mechanism and using the enterprising tag-line: 'A certain flush with every pull'. Looking at his images of toilets he dates the loo in Walthamstow to the 1860s.

Jonathan finally takes his chisel to the wall to look for the blocked up door. His starting point is to shine a torch on the walls so that the beam travels along the wall and picks up all the irregularities - he spots a straight line coming down and a change in the skirting also suggests that this might conceal a blocked door.

After two unsuccessful tries on the ground floor he moves his investigation to the first floor and finally reveals two different colours of brick and two types of plaster. This is where the blocked up door is.  (Top tip - if you try this at home check for electrical wiring before taking a chisel to the wall to avoid electric cables.)

At the Vestry museum Nick's investigation into the index of street names reveals that Jakob's house dates back to 1855, another 10 years older than he thought. There's a puzzle for Nick - he now has to find proof that this is in fact the date that the house was built - but by whom?

 Nick manages to establish that the date of the house's construction was 1854 and an obscure line in the title deeds names Walter E Whittingham. By cross-referencing it with information held in the 1851 Census, Nick discovers that he was Secretary to the National Freehold and Land Society, an organisation which was buying up estates and building houses on them - one of the first things they built was Jakob's house.