Why did UKIP accept Councillor Benjamin Dennehy into their party?

A UKIP councillor has been found to breach Ealing Council’s rules following a controversial blog post that made a series of unfounded accusations about widespread illegal activity and anti-social behaviour by local Asians:

EALING’S first UKIP councillor has been found guilty of writing a blog that opponents say ‘smeared’ people in Southall…

Cllr Dennehy posted a blog post on March 13 2012 over the “beds in sheds” issue in Southall. For its perceived offensive nature, he was expelled from the Conservative Party.

The ruling was by Ealing Council’s standards committee, as Cllr Gary Malcolm (Lib Dem) explains:

Ealing Council’s Standards Committee has upheld the complaint by myself about the offensive nature of Councillor Dennehy’s blog which made a number of unfounded assertions relating to both Indians and residents of Southall. So, Benjamin Dennehy is guilty as charged.

In the meeting [I] spoke about why he made the complaint and read out comments made by residents who stated that his blog was racist, emotive and not based on facts. It was noted that Councillor Dennehy did not attend the meeting, and also ensured a previous meeting to decide this matter was postponed…

During the process which has lasted for more than a year Councillor Dennehy’s delaying actions have meant that Ealing Council has spent approximately £5000 in terms of external legal advice and officer time.

At the time of the blog post, Councillor Benjamin Dennehy was a member of the Conservative Party. However, he was expelled from the party for writing the blog post, something UKIP would have known at the time they accepted him into their ranks. When UKIP made that decision, the complaint against him was also underway.

UKIP can hardly claim it didn’t know what his views were. So why did UKIP accept Cllr Dennehy as a member?