EFLI Testing

Hi guys - need your help please.

Installing a kitchen in a seaside bungalow, I'm testing the fused spur I've installed. EFLI of around 740 ohms. Golly, thinks I. Inspection of the board shows me a PME system (made simple for dimwits like me by putting a sticker on stating "PME"). Further inspection of CU is OK, decent Hager put in by registered NIC Approved Contractor, all very neat and correct, and more to the point had 16mm earth firmly attached.
Pop next door to said contractor, who tghen watches me test and agrees the high reading. He kindly sends one of his guys round next day, who tests at 0.43! Oh good, my Megger needs calibration, despite being done only 6 months ago. I get back home and do a quick test, and it shows 0.45 !!
Admittedly the seaside test was done on No-Trip, and the home test was against non-RCD semi enclosed fuses.
Any ideas before I run off and get my tester calibrated ? (again)

Did the second chap test at the same point??

Lectrician - he tested at all the same socket outlets, on ring final and also on the cooker radial. The Ze test (which I didn't do) also checked out (0.2 or similar, I forget).
Is it something to do with the No-Trip test on my MFT1502 - is this something you've seen before ?

Many thanks....

I have an older megger, i sometimes get funny readings and they become fine when i change the batteries.

Something I did consider, even though this one has a battery-low indicator. But you're right of course, much cheaper than a recalibration.

mine had abattery low thing- plays up for a bit before it lets you know the batteries have had it.

You need the LTW325, Dave.