Morrison left Hotwire last month to launch Babel with ex-Hotwire colleagues Ian Hood and Alexia Sciplino (PRWeek, 4 August).
Ludditt leaves B&B after two and a half years to join Hotwire as head of telecoms for the UK. She is part of the agency's 13-strong telecoms team and is working under Hotwire's regional UK director Brendan Craigie.
Ludditt's clients include Logica CMG, telecoms company Thus and Research in Motion.
‘I will also be looking after new business and will be on the lookout for new developments,' said Ludditt.
Hotwire has around 45 staff in its London office, with another 40 in offices across the Continent.
Ludditt worked in B&B's tech division, reporting to deputy MD David Vindel. Prior to B&B she worked at AxiCom and Catalysis.
Other recent exits from B&B include that of Ben Maynard, who is to return to technology company Harvard after just six months with the agency (PRWeek, 21 July).
Last week it emerged that board director Lisa Quinn is to leave at the end of the month to join the National Lottery Promotions Unit.
B&B's Vindel said: ‘We will shortly be advertising for a replacement for Katy, as well as for four other
positions in the technology comms team.'