great photo but sometimes it is difficult to identify species from photos without having views from many different angles.
Cuckoos are particularly difficult.
Your suspicions are correct-definitely a male cuckoo- possibly a Gypsy cuckoo but I cannot rule out Barbut’s cuckoo bee which is generally rarer but possibly under-recorded.
Barbut’s cuckoos target species such as the Garden and the Ruderal bumblebee.
kind regards, elaine