The two played for the now defunct Perth Reds last season, Higgins in the back row of the pack and Ryan as centre, goalkicker and sometimes captain.
Ryan is seen as a replacement for Greg Barwick, one of 11 first-team squad players who will not be with London next year.
He and Higgins join the New Zealand Test prop, Grant Young, who was signed earlier this week. The club's chairman, Richard Branson, has set aside pounds 1.5m to contract new players, with an experienced scrum-half the likely priority, following the loss of Shaun Edwards to Bradford and Josh White to Salford.
St Helens, who have deferred consideration of Anthony Sullivan's transfer request until they can meet him, have been talking to the former Wigan and Leeds centre, Kevin Iro, who will be without a club if the Hunter Mariners fold, as expected, when the two competitions in Australia merge - a long-awaited event that is anticipated over the next few days.
Warrington have signed the New Zealand Test forward, Brendon Tuuta, as a free agent from Warrington.
The Rugby Football League is to clamp down on trainers, physiotherapitss and water-carriers bringing instructions on to the field. Following a meeting with Super League coaches, the controller of referees, Geoff Berry, has warned that clubs will be punished if they continue to abuse the system of giving on-field treatment.
"The ball is very much in their court. If they [the clubs] abuse the system we will come down heavily on them," Geoff Berry, the RFL referees co-ordinator, said. "The clampdown will initially last for four weeks but, if we see trainers standing behind the defensive line organising play, clubs can expect strong action."
The Bradford Bulls have won the top award from the government's Sportsmatch scheme for encouraging grass-roots sport. The Bulls' successful programme of school holiday activities was judged the best among the 70 sports into which Sportsmatch has directed funds.Reuse content