1848 Treason felony act
3. Offences herein mentioned declared to be felonies
If any person whatsoever shall, within the United Kingdom or without, compass,
imagine, invent, devise, or intend to deprive or depose our Most Gracious Lady the Queen, from the style, honour, or royal name of the imperial crown of the United Kingdom, or of any other of her Majesty’s dominions and countries, or to levy war against her Majesty, within any part of the United Kingdom, in order by force or constraint
to compel her to change her measures or counsels, or in order to put any force or constraint upon or in order to intimidate or overawe both Houses or either House of Parliament, or any other of her Majesty's dominions or countries under the obeisance of her Majesty, and such compassings, imaginations, inventions, devices, or intentions, or any of them, shall express, utter, or declare, by publishing any printing or writing ... or by any
overt act or deed, every person so offending shall be guilty of felony, and being convicted thereof shall be liable ... to be transported beyond the seas for the term of his or her natural life.
Penal transportation was abolished in 1868,
[8] leaving life imprisonment as the maximum sentence.