Hal (or Halle) is a small town west of Brussels containing a well known shrine to Our Lady. The London mission was founded by the Scheut Fathers from Halle to serve the Belgian refugees in London in the First World War. There was a temporary chapel opposite the presbytery from 1921, until the opening of the present building in 1933. The presbytery next to the church is a slightly later addition.
The church has a multi coloured stock brick street front four storeys high and divided into two sections. The original left hand section has a gabled centrepiece with long lancet windows above a triple arched porch. The centre is flanked by a single bay on each side with rectangular windows of domestic pattern and a steeply pitched pantile roof with large dormers. The right-hand half of the front is a large presbytery of three main storeys with a set back fourth storey. This part is wholly domestic in appearance and of three bays of large rectangular windows with a wide central arched entrance. The window glazing has recently been renewed.
The triple arched entrance contains mosaic decoration in the arches, and opens onto a broad passage through the body of building which emerges under a deep west gallery into the wide aisleless nave. The nave roof rests on heavy chamfered concrete pointed arches carried on corbels; the roof itself has exposed rafters and dormer windows. The mostly clear glazed windows in the plastered side walls of the nave are round headed lancets with reveals of red brick. The nave has a parquet floor. There is a northeast side chapel, now separated from the main body of the church by a glazed screen, and an apsed, semi domed sanctuary with three lancets on each side. The sanctuary has modern fittings.