@Keir_Starmer chose not to publish details of the donors to his leadership campaign until the polling had closed. Why was that? Let's look at the donations and the donors.

The only material individual (non-union) donor declared before March 2020 was Robert Lantham's donation of £100,000 (Lantham was a colleague in Starmer's Chambers. We all knew that Starmer's campaign was costing a lot more than that (what did you do with that poster?)

The other individual material donations (I've included those of £15K and above), were declared on the register in March.

Clive Hollick donated £50,000. Hollick is a Merchant banker and media moghul. Also advisor to Peter Mandelson. In the 2015 Labour leadership contest, Hollick gave financial backing to Liz Kendall and in 2016 to Owen Smith.

Martin Taylor donated £95,000. Taylor is a hedge fund manager and had donated c£0.6m to Labour in previous years. When Corbyn was elected leader, he switched his support to anti-Corbyn groups like Labour Together, Saving Labour and Labour Tomorrow

Trevor Chinn donated £50,000. Chinn is a pro-Israel lobbyist and executive committee member of the Britain Israel Communications and Research Centre. The campaign wing of this organisation "We believe in Israel" is directed by Luke Akehurst.

Peter Coates donated £25,000. Coates is a Betting shop magnate and longtime Blairite financier. Coates announced in 2016 that he would not finance a Corbyn-led Labour Party, but would focus on “personal donations to fund [MPs] whose centrist views are aligned to his own”.

Martin Clarke donated £25,000. Finance boss of AA, in 2015 Clarke declared Jeremy Corbyn would be a disaster if he were elected leader and went on to quit Labour to join "Change", and was one of the main architects of the disastrous "Change UK"

It isn't hard to work out what all these donors have in common and why Starmer might have wanted to conceal them. He claimed that he would continue in the Party's recent radical socialist direction, whereas all his backers were anything but.

Finally, the biggest undeclared donation was £100,000 from Waheed Ali, granted a peerage by Blair in 1998. Ali was one of 64 Labour peers who signed a vitriolic full-page advert in the Guardian denouncing Jeremy Corbyn for “allowing antisemitism to grow in our party"

Here's the full table based on data downloaded from the Electoral Commission website