Solution found
A bit slow to reply, but I have sorted the partitions. I used a hex editor and corrected the partition table by hand. Not recommended unless you really know what should be there.
Partition table entries specify the partition by its start and end sector in C:H:S format. As this is a 24 bit field it can only go up to 8 GB. On a disk larger than 8 GB (i.e. all disks these days) the partition is specified by its starting sector number and number of sectors and the C:H:S values are set to 0xFFFFFE. One of the utilities I used, which might actually have been Yast, "corrected" the table by calculating C:H:S values from the physical sector numbers and writing them in - modulo 8 GB.
Interestingly, Windows XP...