Boscobel House in Staffordshire was owned by a Catholic family whose religion was suppressed in England after the excesses of Mary Tudor (reigned 1553-58) and her penchant for burning Protestants. Under Elizabeth I (reigned 1558-1603) the crackdown was reinforced after Pope Pius V, in his 1570 papal bull "Regnans in Excelsis", excommunicated the Protestant Elizabeth and encouraged all faithful Catholics to do all they could to depose her.
Sanction of assassination of the Queen by the pope after the execution of Mary Queen of Scots (1587) and the failure of the Spanish Armada (1588) accelerated the Catholic persecution in England.
Jesuit priests, deemed seditious, were hunted down as traitors.
Rich families who adhered to the Catholic faith were forced to perform their ceremonies in secret and built "priest holes" to hide priests in the event of raids by the authorities.
Boscobel House has two such priest holes, one below a cupboard in a bedroom and the other under the top of a staircase leading up to the attic room (shown in the final pic here).
In the middle 17th century it was this hiding place that was also used by the fugitive Charles II after the battle of Worcester.