Sorry folks, I have been waiting for some developments here, but nothing has happened.
I found that the one I had resonated as follows:-
Instead of 50MHz it resonated at 42
Instead of 70 MHz it resonated at 62
It was OK at 144 MHz and I cannot measure resonance at 432.
2.7:1 at 50MHz
2.2:1 at 70 MHz
1.5 to 1 at 144MHz and 432MHz.
The gain was low (but for an antenna only 1.2 metres long that was to be expected). For 144 and 432MHz it seemed OK, but it was lacking compared to my other antenna at 70MHz and 50MHz. Hardly surprising.
I sent it back to Mirfield a couple of weeks ago but I have heard nothing since. He left a message to say he has received it.
EDIT - I see I sent it back and it arrived at Mirfield on 27 April.
Thanks to John GI7UGV and Chris GM4ZJI for asking about it. I have been so busy getting the rotator working I had not actually noticed that this has slipped off the radar.
Sorry, I must be more positive.
More news when there is some.
EDIT: I sent it back on 23 April and it arrived on 27 April. As I had heard nothing else I wrote an email on 7 June suggesting a refund or I would accept the mobile version as a replacement. Martin has replied to say that he has been on 2 weeks holiday and he sent the antenna back yesterday (6 June). Interesting. I shall await developments.
FURTHER EDIT: The antenna was indeed posted back on 6 June and it arrived here on 10 June. During its absence (23 April to 10 June) some tests were to be done on it. There is a note pointing to "SWR figures you will be likely to achieve", 1.8 at 50.5, 1.4 at 70.5, 1.4 at 145.5 and 1.3 at 433.5. It has been too wet for me to test this so far. The note says that the results are from each antenna mounted on a 10ft fibreglass pole - interesting as I do not use fibreglass poles. Also the antenna should be mounted well clear of roofs, walls, other antenna ... which I did before, but not on a fibreglass pole. It says the tests are done using RG58 coax. I used RG213 as I find RG58 is lossy. As a result RG58 tends to disguise high SWR by absorbing the reflected power into general losses, especially at 144 and 432 MHz. I will try to test it tomorrow.