Looking through passenger lists for the Martyr families has not been successful so far. It is not an easy job. Not all lists are online, and with many, the writing is terrible.
Passenger lists are very helpful in determining who came with whom, and when, and from where to where.
In the case of the Tolpuddle Martyrs, one of the key questions relates to James Loveless and his family. James had married Sarah Daniel, and with her had 3 children. The youngest two died whilst James was in Australia, and at the time of his emigration to Canada in 1844, there were only his son Eli, aged 13, and Sarah, his wife.
We can find no trace of Eli or Sarah in either Canada or England after the 1841 English census, and it is not known whether they actually came to Canada or stayed behind. A passenger list would hopefully answer this question.
It is believed that the Loveless and Brines arrived in Canada in the spring of 1844. They most likely would have come by sailing ship. Steamships really only came into their own around 1860.
The transatlantic trip likely took about 6-7 weeks, and so if they left in February, they would have arrived in April.
Most likely they departed from Liverpool, rather than Southampton, mainly because in the age of sail, Liverpool was the major transatlantic trading port.
In terms of arrivals it would likely be either Montreal or New York. In both cases, they probably made their way to Hamilton, from whence they travelled overland to London, Ontario.
Efforts to date to find the Lovelesses or Brines or the Standfields (in 1846) in passenger lists have not been successful. (But please keep looking!)
They most likely came across in steerage, and in the early days those in steerage were not always recorded.
Another reason they may not be found in passenger lists is that given their notoriety, they may have travelled under assumed names. They may have wanted to avoid any difficulties on the boat from people who might regard them as troublemakers. For certain, English passengers would have at least heard of them, the huge public outcry of injustice, and the massive Copenhagen Fields rally, but likely wouldn’t recognize them in person. Many were in sympathy, but their recent involvement with Chartism in Essex was not universally regarded favorably. Of course, once in Canada, they reverted to their own names. Please note the “assumed name” conjecture postulated here is pure unsubstantiated speculation.
But the searches to date have not been exhaustive. I have a hope that a list might exist for at least one of the voyages, ie the 1844 voyage or the 1846 (Standfield) one. Perhaps they are on microfilm somewhere. If someone had the inclination, time and interest, it would be useful to first compile an inventory of ships and sailings that might be candidates. With that a more coordinated search effort could be organized amongst willing volunteers.