IS for disability - reaching the PC age

I’ve been asked to help a colleague with a client who currently receives IS on the grounds of disability. He’s recently received a letter to say that his IS is stopping because he’s about to reach the PC age.

However, he has another recent letter to say he’s not entitled to ESA because he didn’t attend a WCA.

I was thinking that he should be moved from IS to PC with transitional protection if necessary. I’m assuming that ESA claim is a mistake - either because the DWP tried to transfer him to ESA not realising that he’s nearly PC age (but that seems unlikely), or that he mistakenly made a claim for ESA and the DWP mistakenly allowed the claim to proceed to the WCA.

Is it possible/advisable for someone to claim ESA just before reaching PC age so that they continue to receive it after they reach PC age? Is it beneficial because the transitional protection in PC gradually reduces whereas ESa wouldn’t?

You can’t carry on receiving ESA once you reach pension age - see p.27 Welfare Benefits and Tax Credits Handbook 2015/16.

If you’re receiving IS, JSA(IB), or ESA(IR) immediately before you become entitled to Pension Credit, you receive transitional protection if your entitlement to PC is less than it was under the 3 benefits concerned - p..137 WBH.