Leman House was built around 1570 and was completely restored and modernised in the 1760s. Originally it was a timber framed structure, much of which disappeared when the brick facades were added. What remains shows minimal decoration, but it still shows the classic features of a mid 16th Century building, including a series of fine Queen Post roof trusses in the attic.

In the 1760s the delightful facade facing the street was built of flint and brick, and pantiles were substituted for the previous thatched roof. It was also at this time that the Gothic shaped windows were introduced.

When Sir John Leman gave the building to the town in his will in 1631 it was already a school. The payment of the master and usher came from income from land outside Beccles, which Sir John gave at the same time for the school's support. The foundation was for 48 boys who had to be able to read and write before entry. Pupils were to remain at the school for four years.

Of the many headmasters of the school, one of the most notable was Robert Davey in the late 18th century. He was a founder member and first Master of the Apollo Lodge of Masons in the town and was commemorated by a fine memorial in St Michael's Church. He painted the Leman Arms on the north end of the house. He became Headmaster at the age of 19 and remained for 35 years until his death.

The free school closed in 1905. The building had several owners during the 20th Century, one that is often remembered by Museum visitors is the PNEU School of the 1950's and 1970's.  In 1994 the building was acquired by the Townlands Trust and underwent significant renovation and repair. In 1996 the Museum was offered the use of the ground floor of the building and it is these four rooms that are now available for the public to visit.