I've not had a chance to look closely at all these donations, but it's worth noting that what is classed as a donation is quite broad. To give one example, I was recently surprised to see that a local art gallery had apparently made a donation to my MP according to some data highlighted by the press. However, digging into his parliamentary register of interests, he had actually run a community jobs fair at the centre and they had provided the space free of charge, which was counted as a donation in kind. A worthwhile cause, and, to my mind, nothing improper about them offering the space for free.
Similarly, I looked at the Siemens donations to Michelle Donelan MP mentioned upthread, as the register for MPs is more detailed and fairly quick to check. They relate to the Wiltshire Festival of Engineering and Manufacturing, which she organised in 2016 and 2017, rather than being contributions to her re-election fund or similar. Were Siemens donating to the Festival to curry favour with her? Possibly. Were they donating because they saw it as a recruitment/publicity/community relations opportunity (they have a facility in her constituency) and would have done so even if it had been organised by someone else? Possibly. From the data you can't tell, and both are plausible reasons (and, of course, not at all incompatible).