Donating profits to a charity - what about expenses?

A retired client had a source of self employment (writing medico legal reports and giving lectures) but has scaled this back to sitting on a couple of committees and giving an occassional lecture when asked.  They still incur related office/travel/techincal costs, although the fees are 'modest' - probably no more than £5,000 per year plus expenses.  They request that any fee from the lecture circuit is made out to a charity of their choice rather than to them personally.  Aside from this activity, they have a resonably good pension income that puts them well into higher rates.

My gut feeling is that this isn't trading, as there is no real profit motive here.  That said, the individual is contracted to be on the committees and to lecture, regardless of how little they are paid, or what they ask to be done with their fee (in the case of the lecture income), so I could be swayed the other way!

Does donating the lecture fees mean there is no profit motive (and so no trade/allowable loss on this element of the income), or is this just a trader who wants to give something back?  If it were a trade, how do the gifted fees get treated?  They're not made under Gift Aid by the client, so are they deductible as charges on income against the income received - potentially resulting in a tax 'nothing' on the lecture side of things?  What about the expenses they incur?

To be honest, a lecture fee/donation of say £500 would probably be worth more to the charity coming from the individual (net) rather than a company (gross), as they would be able to claim higher rate relief on the Gift Aid donation personally.

Any thoughts?