Dr Phillip Lee, MP for Bracknell, has been named as the new justice minister to oversee the changes to cremation laws following the baby ashes scandal in Shrewsbury, replacing Caroline Dinenage MP who now has a role in the department for education.
Glen Perkins, leader of Action 4 Ashes, said he will have to wait and see what impact the replacement will have, but says he will always be thankful to Ms Dinenage.
It comes after a number of landmark changes to laws and regulations were revealed last month to ensure historic practices at Shrewsbury's Emstrey Crematorium are not repeated.
He said: "I don't yet know what he has to offer us. I am a bit disappointed we weren't told, in respect of being part of this new working group, but now we have to start the process to find out what he is going to oversee.
"We need to see if he is going to keep overseeing the things she has set in place and if the National Cremation Working Group is going to remain the same."
The campaign led by Action 4 Ashes for changes to the cremation process prompted a Government-led public consultation.
The findings, released last month, led to an announcement that there will be the introduction of a statutory definition of "ashes" and will also bring the cremation of babies born at less than 24 weeks' under regulation for the first time.
The campaign also led to the introduction of the National Cremation Working Group which will consider changes, and the potential for an introduction of a crematorium inspector.
Mr Perkins, who was recently asked to be part of the group, said: "I have already started asking questions to find out what the state of play is and I have read a bit about him.
"He is a doctor and part-time GP, so he has a medical background.
"We do have a problem with a medical profession already so I hope it won't throw a spanner in the works."
An investigation launched in 2014 found as many as 51 families were not given ashes following cremation of their children at the crematorium in London Road.
Mr Perkins, whose four-month-old daughter Olivia died in 2007, started the group and said he was grateful for everything Ms Dinenage had done. He said: "Caroline has been more than decent since we first presented this to her.
"She has been very helpful and understanding and I can't thank her enough.
"She has been fully above board with us and she has acted swiftly and that is the kind of thing I would now like to see continued."