There were many Wars of Religion in Europe at the time trying to decide on the French Throne. Protestant England supported Navarra while Catholic England supported The Catholic League (French, The Pope and Philip II of Spain)
Some of the conspirators behind the plot had been worried about some of the Catholics that would be present in parliament on the night of the explosion.
An anonymous letter was sent to one of them warning them not to attend parliament on this night.
On 26 th October 1605, Lord Monteagle read a letter saying;
My Lord, out of the love I bear to some of your friends, I have a care of your preservation. Therefore I would advise you, as you tender your life, to devise some excuse, to shift your attendance at this parliament; for God and man have concurred to punish the wickedness of this time And think not slightly of this advertisement but retire yourself into your country where you may expect the event in safety, for though there be no appearance of any stir, yet I say they shall receive a terrible blow this Parliament and yet they shall not see who hurts them. This counsel is not to be contemned, because it may do you good, and can do you no harm, for the danger is past as soon as you have burned the letter: and I hope God will give you the grace to make good use of it, to whose holy protection I commend you.