Neil Hopcroft

A digital misfit

Book review: In code by Sarah Flannery

Sarah is the Irish schoolgirl who shot to fame in 1999 when she created a new crypto algorithm. The algorithm has since been attacked to the point where it is not considered useful.

The book is about her exploration of number theory, what happened when she worked with Baltimore, the crypto company, and where that took her. She is doubtless a bright star of mathematical talent, and, if this book is anything to go by, communicating that in a way that makes it easy to understand. It takes a tour through the mathematics, and suggests some good ways to go about teaching maths to keen but unknowlegable people, through the school competition circuit, and on, to the international competitions.

One disappointment, for me at least, is that she doesn’t describe the Cayley Purser algorithm itself, this might be modesty or because of its discredited status. She is very clear about her desire for the algorithm to be fully analysed before anyone got too excited, but the press got carried away with the potential.

But all in all, a very interesting book, written by an intelligent communicator. I have a lot of respect for Sarah now, Cayley Purser may have fallen, but she is worth keeping an eye on, there’ll be more good stuff from her in the future.

Who should read this book: anyone who is interested in cryptography, but doesn’t have a strong background in it, will appreciate the easy to understand mathematics, this isn’t to say the maths is easy, far from it, but the explanations are good. It will be a bit simplistic for the kinds of people who code crypto daily.


I’m considering going walkabout next month – I’m owed some holiday from work and I’m wondering what to do with it.


[Money] Some notes about asset allocation and stockpicking strategies

Nearly ready to launch into the kinds of posts I was really intending to do for this series. But first a few notes.

A couple of people have asked about how I arrived at my asset allocation, so I thought I’d lay out what my thinking is. You’ll get different stories about what you should do depending on who you talk to, some people say you should have six months salary in cash available immediately, some that you should short sell the main market index when you leave college and gradually cover your position (the thinking here is that you have some human capital which will erode badly if the economy slows, so you want something to hedge that and shorting the market does that).

Some factors here are that I’m in a position where risk-taking is not deeply problematic, I’m single, without mortgage, and if worst comes to worst I have family I can run to. This doesn’t mean I’m taking insane risks but it does give me a bit more flexibility to take on more risk than most people can stand. This is, however, tempered by the fact that AIM stocks cannot be held in ISAs, so all of my (current) portfolio of stocks live on the main market.

As for selecting between cash, property and shares, that is in part driven by tax efficiency and in part by opportunity. Being to precious about keeping everything balanced too accurately will lead you into moving away from good perfomance investments to poor performers. It really doesn’t matter that much – because nobody can see the future well enough to say that any strategy will be better than any other – as long as theres a bit of diversity in there, ideally with low correlations. The share portfolio started as a ‘1000 pounds I could afford to lose’ gamble, which taught me enough about what it felt like to lose money that I figured I could deal with it.

So how to pick stocks? Well, I read Investors Chronicle, which is a tedious financial rag but which contains commentary on and summaries of company results. There are some things I’m looking for, a company that has rising turnover, rising profits and rising earnings per share (ideally for the last three or four years and with profits rising faster than turnover) will narrow down the list of candidates from the 40 or 50 companies they cover each week to a list of maybe three or four.

Each of these is then worth investigating a little more, quite often they already have a ridiculously high price-earnings ratio (anything above 20 is way too high), which means most of the coming upside is already built into the price. The next consideration is whether my current portfolio is already too heavy in their market sector, this wouldn’t necessarily prevent me buying but it is worth considering.

These companies then form a list of candidate shares – a lot of them will be rejected for some reason after reading the write up, those that are not are candidates for buying.

I tend to use a fixed amount to buy in, so all of the shares I own I bought the same ‘value’ of, subsequent moves have adjusted their weighting within my portfolio. Right now I have 1 ‘value’ available inside the ISA wrapper for spending on another company. This will be increased in December by another ‘value’ when the Amstrad special dividend arrives.

The danger of this strategy is that it has a tendancy to pick up five year cyclicals at the top of their cycle, which is why I’m a bit light on builders. And I don’t know whats going on in commodities at the moment, so I’m sitting out of mining and oil.


Book review: Brainwash by Dominic Streatfield

“The secret history of mind control”

This is an interesting book, it works its way through a number of attempts at mind control. It covers truth drugs, hypnosis, torture, subliminal advertising and religion.

There is a lot of good detail about the background of some of the experiments done by the CIA into finding truth drugs. Reading this, though, was a little disconcerting since it was putting a series of things I thought were conspiracy theories into a very precise historical context, either this is part of the conspiracy or they actually happened.

Beyond this there are descriptions of many attempts to make a Manchurian Candidate and extract information using torture and drugs, and how to resist such attempts.

All in all, an interesting book, pulling together a nice collection of information about attempts at brainwashing and controlling peoples thinking. None of this is much of a surprise, but its good to see it brought together with a lot of detail about how things fit.

Who should read this book: anyone who is interested in mind control, anyone interested in conspiracy theories.


[Money] Current situation

Currently I have three asset classes, in roughly equal measures: property, cash and shares.

I don’t own the flat I live in, mostly because I don’t anticipate staying for long enough for that to be worthwhile, this has been the case in most of the areas I’ve lived in. The property is a house in France owned with two others. This is currently being renovated. The house is roughly 25% funded by debt, which I’ve borrowed from a company I (mostly) own, I am recording its value as being the amount I have spent on it, this is perhaps not acurate but will be a good enough measure for the purposes of these discussions. I anticipate a further expenditure of 20% of the properties cost every year for renovation and improvement, this expenditure will be added to the ‘book value’ that I record.

Cash is mostly sheltered from tax by ISAs. This isn’t very exciting.

I have a portfolio of 16 shares, most of which I’ve held for more than a year now. These also live within an ISA. I intend to hold these until the time is right to sell them. There have been a couple of shares I’ve sold when the company changed from the company I was thinking I was investing in. The current companies are Amstrad, Castings, Charter, CareUK, Evolution, Goodwin, Helphire, Hornby, ICAP, nCipher, Premier Foods, Psion, RBOS, Spirax, SCS and Trifast. Some of these have done better than others – the best is up around 200%, the worst down around 40%, overall the portfolio is up around 20%, compared with cash which is up around 10% over a longer period. Of course the volatility of these shares is significantly higher than cash. This portfolio hasn’t had any rigorous allocation strategy or risk management thought – it has been more a case of finding shares I believe will do well and investing a reasonable amount in them, it has to be enough that dealing costs are easy to recoup.

This whole lot totals to less than a years salary, but it is positive. I have two bits of debt, both of which are covered by cash, they happen to be better run as debt than spending the cash (mostly this is more tax efficient) – a loan from my own company for part of the cost of the house and a credit card bill I forgot to pay this month (min payment covered by direct debit). The loan from the company needs to be repaid before June because there will be some tax implications if it isn’t.

So, this isn’t about getting out of debt….what is it about? Well, the aim is to get my finances in such an order that I can live off them without having to work full time – obvious not having to work at all would be great, but thats a bit further off. Perhaps the ‘not having to work full time’ actually means taking some months each year and living in the house in France. Right now I’m covering around 30% of a months salary per year in passive income – this is clearly nowhere near independence.